I very much like all your comments in this thread. I'd like to frame the last one.

I'm replying here because I hadn't seen the connection between Buffy choosing to go back here and her huge despair at being forced back in season 6. It's obvious once you say it, and I like that it picks up something that had bugged me about season 6 -- namely Buffy's sense that everyone was OK. I've always thought that was a flag that 'heaven' wasn't an unproblematic paradise -- and I like the development of that theme here.