Jesse I got more of a sense of sheer adrenaline fuelled, maniacal elation. But obviously in his case the assumption has to be that that will quickly subside into utter heartbreak, as you say. The minute he's alone he has to deal with the fact Andrea's been murdered, he's been kept as a slave for months, is responsible for the murders of several people (directly or indirectly) and that the one person who has a shadow of understanding of what he's been through is now gone. On the surface of things he's young and free to do as he wishes, but it's very hard to imagine him having a happy life once that initial elation has gone.
Skyler I thought was more interesting. After saying goodbye to Holly, the looks Skyler and Walt share before he leaves the room and the way Skyler clenches her fist after he's walked out, as though part of her had wanted him to say goodbye to her as well, I thought was very intersting. To me it showed that no matter how much he'd done, how she'd accepted he was no longer the man she loved and that for him to die was the best outcome, part of her still held affection for him and wanted him to reach to her in that moment.
In both cases I think they still either saw glimmers of the old Walt or felt that the memories were still strong enough that they could remember he was once a good man.
Hmm, hard to explain any of this without sounding like a wanker really...