I'm only into page 8, and I see both sides to the argument. ( and this turned out longer then I thought)
If Sansa kept shut about the Vale because as Risto states, that she didn't want to be forced into a choice but have THE choice, sort of comes off as selfish ( at least to me ) the moment that the pink letter came to the wall that argument is moot, the choice to refuse LF is hers ( because Molestown was before the letter), the choice to not tell Jon after she sent the letter is not. Sansa is now involved with plans to retake their home and it involves herself, Jon, Brienne, Davos, Millisandre, Tormond and his 2500 fighters and whom ever else they can gather, at the least she should confer with Jon and let him know that she refused LF because of what happened to her, again I based these actions at before and after the pink letter arrival.
People who say Sansa is an inherently evil bitch, and only cares for herself, or wants Rickon, Jon or others killed so she can have Winterfell for herself don't read, or they are looking at a different show in my opinion.
In the beginning of the book and show Sansa does come off as snobby, elitist and very naive, but she has never done anything remotely evil ever; the show cut out and changed things from the book, due mostly to time constraints but also to bring each character to their central points, they cut out the part where Sansa vouched for Arya to her father and changed the scene in front of Robert to have Cersei call Sansa to tell what she saw and Sansa lied to the King, but did not vouched for Joffry nor did she deny what Arya said to her father, she played the middle and got burnt. We then see Cersei demand a wolf and Robert gave it to her, and Ned doing the deed and sending Lady home for burial and the subsequent sibling feud between Sansa and Arya and they add the Ned talking to Arya scene to explain why Sansa did what she did and ends it with Arya asking her father "how can you let her marry someone like that"? Ned had no answer.
They eliminate Sansa running away to Cersei so she can say goodbye to Joffry ( though if they bring it up later in the show it can change things )and cut straight to Neds actions of confronting Cersei in the God's Woods, his changing the Kings last words, LF's betrayal, Sansa's plea for her father's life, Cersei forcing her to write to Robb and Cat ( yet Sansa still asked to see her father to ask before writing) ending with Joffry's betrayal and Sansa's retort about heads and her attempt to push the new King off the wall only to be stopped by the Hound, nothing here points to Sansa being evil or self centered, just naive and foolish .
From season two and book two on we see Sansa evolved she listens to Sandor and starts playing the mouse going below radar it keeps her from the King and Cersei's attacks along with the help of Tyrion and Bron now in Kings Landing,Sansa is continuously being mentally tortured by Cersei and Joffry and almost ganged raped ( to be rescued by the Hound) she saves Dontos life by coming up with a false saying about killing someone on your birthday, she tres to manipulate the King into fighting at the head of the battle instead of from behind, she calms the people in the holdfast and gets aid for Lancel Lannister after Cersei hits him and runs off with Tommen on a murder suicide attempt. She calms the Hound before he leaves and refused his offer to go with him; some people think this was a bad decision on her part, but was it?
The Hound was drunk ( and in book violent ), Stannis was winning she was next to Cersie and Lancel when Lancel said the war was lost so as far as she knew she be rescued, except Tywin should up and defeated Stannis a situation she could not foresee, nor did Cersei either.
From this point on Sansa continues to lie to the Lannisters, and she puts trust in the Tyrells as they offer an escape out of KL she still shows her naiveness by confiding in Dontos not knowing Dontos is working for LF, there's a lot Sansa doesn't know about LF, nor do the Lannisters, the Tyrells, Tullys, Arryns etc. she's only 11/12 in book and 13/14 in show. She cries and is angry and depressed over the death of her mother and brother, she feigns going to the Gods wood (depending on the medium you follow) She puts her trust in Shae not knowing she's working for Tyrion, Sansa is continuously being mentally tortured by Cersei and Joffry until LF and Lady Olena decide on a course of action that frames Sansa and Tyrion for the King's death; and is subsequently told by LF that he is taking her home. Depending on the medium one chooses to refer to, Sansa figured out on her own what LF and QOT did or she is filled in on the info; again there is nothing here showing or hinting at some evil selfish bitch who doesn't care about family, just a young girl using what she has to keep her alive and eventually out of KL.
Now we get Sansa in the Vale and (in show it's a major departure from the books)we get an Aunt who welcomed her but secretly hates her and also jealous of her niece,we have betrayal to her by her Aunt and her Husband (LF) we have a bratty and dysfunctional child who is being manipulated by a sinister step-dad and we have Sansa continuing her game of innocence and lies and it's here (again depending on the mediums we use) people claim it's proof that Sansa has turned full evil, doesn't care about family ( people forget the snow castle scene? ) or wants to kill her cousin Robyn etc. because she lied about LF; but again ( depending on the medium) she is betrayed and manipulated by Lysa and LF in each case though the wordings are different Sansa discovers that her Aunt has killed and lied for LF, her Aunt threatens Sansa life with her trying to throw her out the moon door, LF kills Lysa ( and in book pins it on a person who attempted to rape Sansa) and again slight changes in book and show in book she's manipulated to lie, in show it's her choice but in each case she has good reasons ( at least in her mind ) in book she doesn't trust the Vale Lords and she tells us they gave no support for her brother, why would they support her, in show when LF asked her why she answered; if they had killed you what would they do with me? and his reply was; I don't know and hers was neither do I . Back in her mind she has knowledge, but she has no proof to pin it yet, and there is more against her ( LF manipulations) that may be hard to prove that she is innocent.
We see Sansa and company down from the Vale and Robyn in the hands of Lord Royce and from here totally off book.
Season 5 we see Sansa figuring things out, giving Brienne warnings that Brienne and Pod ( though Sansa didn't know he was there )were in trouble and she should leave, Balelish still leading Sansa on that a marriage proposal was for him and not her until they were overlooking Mote Calin and Sansa refusal and subsequent giving in; and despite what the show runners say was a choice, it really wasn't. As stated in show and books many times over vows, choices etc under duress or any other way forced isn't a valid one, I can reasonably think that if Sansa refused, LF would do as he say turn back the horses (HE did not say return to the Vale) return to the inn and have the Bolton's get Sansa there.
Now we see Sansa stare down the Boltons and even arguing that they are not the rightful owners of Winterfell ( and it can be argued if that was wise or not ) which under the circumstances is understandable but it marks the end of her hiding who she is A STARK of WINTERFELL, we see her in the crypts paying homage to her ancestors the talk with LF where she noticed he's dressed for travel, LF possible knowledge of some history between Lyanna and Rhegar, his thoughts how Sansa will be saved and his answer when Sansa questioned what if his plan doesn't work out and (despite what the show runners stated that LF actually didn't know about Ramsey)his make the boy hers, something Sansa said she didn't know how to do that.
If we go by what the show runners absolutely stand by and how season 5 episode 6 turned out the only basis for this is to make LF her solid enemy added to what else she knows.
Now from the end of season 5 and Season 6 we see the results of Ramsey on Sansa, on Theon, Sansa using words on Theon that LF used on her ( your Sansa Stark.../your Theon Grayjoy....)she learned and understood how LF manipulated her and is trying to do the same to Theon, the difference is Ramsey is a sadistic nut case and Theon is very far gone, yet we see when Theon returns she changes tactics and she eventually learns her brothers are alive, before that she is called for by Ramsey and she picked up a corkscrew, and learns that Jon is the LC of the Nightswatch, then Ramsey shows her the old woman who greeted her as Lady Stark and the North Remembers, who let her know she has friends beyond the gates of Winterfell, she cried not just for herself, but I tend to think for the old woman too, this made her double down and changed tactics with Theon as stated above.
They escape and subsequently saved by Brienne and Pod only to have people say she didn't help herself, or she didn't fight back when the Boltons caught up with them, or she's stupid because she flubbed 5 words of a vow ( I want to remind those people she started that vow and ended that vow on her own she just for got a part in the middle) that she did not expect to give specially after running from a posse and dogs, traversing a fast running frigidly cold river, no food, wet clothing etc. I want to see those people go through what Sansa did and recite their countries national anthems, hell 99% of us can't recite them in their entirety sober and warmed on a sunny day.
She smiles and happy to here that Arya is alive at ease with Brienne telling her that the man was protecting her, she continues to show empathy for Theon, promises to vouch and protect him at the wall when they meet Jon etc.
At the wall she and Jon meet; nothing there is faked as far as I saw; it was all true happy emotions. We don't get to see each other's reaction to the others stories so we have to interpret for ourselves what went on so I can see Sansa not fully believe the Jon and the re risen scene until she actually sees WunWun and maybe Jon's scars, Jon has no doubts about Sansa I'm sure and will protect her as best he can yet Jon is very bad at picking up on others emotions, his NW brothers, Yigrette, Ollie etc those are people who tried to kill him because he did not pickup on the true feelings they were showing him, Jon was looking at one thing only and not totally explaining or seeing what they needed.
Now we come to the part of what they will do, where will they go, Jon doesn't want to fight anymore and this is understandable he died and he was brought back, he's scared as hell he knows just what Tyrion has always said DEATH IS FINIAL is true and he wants to retire to a quiet place ( don't we all), Sansa on the other hand has been beaten, raped tortured mentally abused etc. for 6 years and she wants to retire too, but she wants to go behind the walls of Winterfell, she feels safe there, stronger too, she has also learned better than Jon how to read people and political landscape and when she tells Jon they have to fight for THEIR HOME and ARYA's,BRAN and RICKON she was being truthful and knowledgeable she knows damn well that none of the male Starks would be allowed to live and her and Arya would be used to gain Winterfell and the North , she wasn't manipulating him, or goading him she was telling him the hard truths ( those words are used a lot ).
We see an opening scene where Sansa is stitching leather she's making Jon a new outfit and she gets a letter from LF, she takes Brienne with her and faces LF, she doesn't want his help, she doesn't trust him and she's got 6 years of reasons not too, but she doesn't have Brienne kill him and it could be because when all is said and done she is away from KL, she's alive and away from him and she feels safe ( but she still doesn't know of his involvement with Cersei at KL and putting Sansa's head on Winterfell's wall, or his betrayal to Ned ) she also doesn't want him anywhere near her family especially her brothers because she knows just as she knows why Ramsey is a danger LF will arrange for some deaths, her brothers are an impediment to his plans. Sansa is correct when she said to him your either a fool or my enemy as she recounted what happened to her but instead of having Brienne kill him she tells him to get out of her life and never see her again, we can see this as her being honorable or foolish; sure as hell no hate or evil intentions on her part.
Littlefinger then drops the Blackfish line and we see Sansa take it in then we see them eating and the arrival of the Pink Letter, Jon going back into denial and Sansa forcing the issue especially when they learn that Rickon is a prisoner, we also see her lie to Jon on how she learned about the Blackfish technically she is not under any reason to inform Jon that she met LF at MT or that she repudiated him and she may see the lie as a way to keep LF from her family and Jon as he is a direct danger to LF plan. We get a view of Brienne calling out Sansa on the lie, and a look on Sansa's face is one of regret even being sorry for the lie, not one of some kind of master plan on deceiving Jon, I think it's more she doesn't trust his entourage, hell Brienne doesn't trust them either, Sansa task Brienne to talk to the Blackfish and ask for his aid, just from what I know from season five and six I didn't need to know what was said in the letter to her uncle, I know from what I see and read she ask his help to restore House Stark, not help me get my house back .
We then get the travel to other houses and both Jon and Sansa fail badly Sansa more because she has been away from the North for ~ six years and she doesn't know the full extent of how Robb's actions affected the other houses; and Jon because I believe he's not good at talking with females especially ladies in power as Lady Mormont is luckily they have Davos and he gets the Mormonts on their side, they then try house Glover and Sansa still naive thinks that the other house have to back her house because honor compels them to and because she believes in her father when he told her the north is different, and just like Davos told her when she basically stated them at Castle Black, Lord Glover reminded her that as of now House Stark is dead and no one will die for a war that is lost, or for a lord who put his interest over his subjects.
Now we get the first real scene where Sansa is demanding that they go for more men and Jon demanding they will fight with what they have, cut to Sansa and the letter, asking for the Vale, she words the phrase properly rewarded ambiguously .
Now do I think Sansa is obligated to tell Jon about the letter? no, not yet, when?
On the morning of the parlay when Jon tried to goad Ramsey and Sansa ask for proof that he has Rickon and Lord Umber threw Shaggydogs head on the ground I think at this point three thoughts hit Sansa,Your going to die tomorrow Lord Bolton; sleep well. Rickon is already dead in Winterfell, and three she hasn't heard from LF ( and I think it's all in keeping with his plan of attrition ) and she will need to make a decision to go get him, it's between the time she left the parlay and the war strategy that she should have told Jon of a possibility of the Vale, no guarantee, only hope and I agree Jon kept asking and she could have mentioned the letter but I think she still had valid reasons in her mind on why she didn't.
I also think Jon's weakness to see, convey emotions and to look only at a situation one way played a part, most people pick up on when a person stress over and over on one thing, like we need more men over and over, most people close to those who are overly stressed could pick up the signs of someone holding back; instead of asking what would they do a lot of people would pick up on the fact that that person has something they're hiding and want to let it out, I don't think Jon saw that, doesn't totally excuse Sansa from telling Jon the possibility of men, but if he picked up on it he could have tried to draw it out instead of asking what would she do.
As far as Jon's strategy, if he had a guarantee that they were coming he could have incorporated them in, I'm not sure it cut down on deaths as I'm sure LF would have made sure to take his time to get there at the last minute. We know also that they got Brienne's letter and the BF couldn't help them because Jon stated it in the tent.
I think after the argument and seeing that Jon didn't hear her or understand her, that she felt she had to GO get LF, it could not have been real close because it looks like it was many hours between the argument and when the Vale showed up.
As far as Sansa giving up on saving Rickon, as I said, I think she thought Rickon was already physically dead, and never thought that he bring him on the battle field to goad Jon, she knew Ramsey do something she didn't know what.
As far as Sansa enjoying the kill, I think that smile was confirmation the Ramsey has disappeared, and she will have no more thoughts of him.
Also about that scene it looks like those kennels were already opened, I don't think Jon opened them but I do wonder if Ramsey did in anticipation of a victory.
Sansa has always kept her emotions in check ( Books more then Show) it's a protective mechanism, I think it was the same for Rickon, if she dwells on it she will loose her control in front of the troops and Jon, and come off as weak, she will let them out behind closed doors just like in the books and like in the show when her mother and brother were killed.
As far as wanting Jon dead and falling for LF I don't see that happening, nothing in episode 10 shows that.
We get the White Raven, we get Jon and Sansa on the battlement of Winterfell with the symbolic separation of the two donating conflict ahead ( anyone who thought this was going to be totally sweet isn't paying attention nor if people seeing this as Sansa turning evil) We see Sansa let Jon know she was wrong in not letting him know about the Vale ( yes it be nice to know her reason but tension needs to be created ) and to her Jon's a Stark and She is the Lady of Winterfell a nice moment calling back Ned's words finally being true.
We later see Sansa under the Heart Tree in the Gods Woods Baleish excusing himself for interrupting her prayers and Sansa saying she's through with all that, yet at the same time realizing she always had what she wanted at Winterfell even though it looked brighter and better on the other side of the kingdom ( just as today people dream of marrying kings, becoming a big star, or leader of a country ) you know just like you or me, our kids etc yet as far as I know no one call us or kids evil or manipulative for wanting dreams, but somehow Sansa gets these arrows.
We see LF start his manipulation again and he starts telling Sansa HIS dreams and wants which seems to go beyond what Sansa thought and he attempts to kiss her and she shoots him down , a hand on the chest, pulling back of her head, words from her lips a pretty dream , a second try; word will get out I through support for the North.... who should the north follow a true child of Ned Stark and Lady Catlyn .....or a bastard with no name; a second reply ( at this point I think Sansa would be wiser to keep it to her self ) You have given your support to other houses Lord Baleish ...... doesn't mean you won't do it again, Sansa leaves him alone in the Gods Woods, but she also know he going to pit Jon against her on his bastard status.
Final scene Yohn Royce is speaking sort of insulted that the wildlings were there, Lord Cerwyn saying the war is over lets go home, LF looking over the room ( at this point I think the book story in blending back in but the writers move it to WF ) he's looking for allies, we know from Cersei she is having birds sent to the North, we hear Lady Mormont scold the older lords, the North proclaiming Jon KITN, there are two / three things here to notice : 1, Sansa is fine with Jon being named KITN it beat LF plan ( at least for now) 2 and 3. only time Sansa did not look happy was when Manderly gave credit to Jon for avenging the Red Wedding this could be a stickler, but Jon up front and personal told her they are there because of her actions and why she is the Lady of Winterfell finally that last look, I don't know how people read that as Sansa agreeing with LF yeah your right I'm being screwed; that was a total look that went from a smile to a look of oh,oh he's pissed and we have a problem, his look wasn't one of I told you so, his look was of one that he made an incorrect assessment and Sansa picked a path he didn't expect.
And anyone who wants to bring up what Sophie, or Liam, or Kit or B & W say later, yeah going to be conflict already been set up but it's also smoke screens, there is nothing in the last scene that shows Sansa turning evil, if anything it's a war between LF and Sansa for Jon or a war between LF and Jon for Sansa at this point I'm going with LF Vs Sansa, she knows his plan, she knows he's a danger to her house, her family, especially Jon and Bran and I think she do anything to protect them even if it means tarnishing her name or even dying.
Holy S this was long.