Palmer wouldn't play for Buffalo. He strikes me as a guy who only cares about the chance to win, and even if Buffalo is improved, he won't have a chance to seriously contend. Teams I can see him accepting a trade to, in order:
Cardinals: They had, possibly, the worst QBs in the league last year. Put Palmer in this situation and they become a vastly improved team; it wasn't so long ago that they went to the Super Bowl.
Vikings: Not a bad team, unless age catches up to them. I can see Palmer wanting to play there, and they'd probably pull the trigger.
Browns: They're probably only a consideration because Cincinnati and Cleveland are relatively close by.
Raiders: Oakland isn't terrible, although I think Jason Campbell is a solid player. It's unclear how Palmer would feel about playing for Al Davis, though.
Redskins: Less likely: owner has a bed rep, and the time would need to acquire someone like Santonio Holmes in free agency, plus a running back. If they make those moves, Washington has a shot.
Miami: They reportedly want to stick with Henne, but they're not a terrible team and certainly have the cash for free agent splashes.
San Francisco: They probably want to try out Alex Smith and Kaepernick, but as someone stated, he's from northern California.
Another option: there's always a decent probability of an elite QB going down early in the season, and without the organized workouts, players could be particularly suspect to injury at the beginning of this season. The trade deadline may even be lifted (who knows?) and if, say, Brady's knee gives out again from a hard hit like Pollard's, that team would pick up Palmer in a second.