Chafee won't be anyone's running mate. He's not that good at debates or public speaking, unless it's something he's truly passionate about (like national service). Big crowds give him nerves. And he personally dislikes the ceremonial stuff, which is a lot of what the VP is.
Blue,
Your point is taken. You are from Rhode Island, and would know better than I. Is Chafee progressive enough for you? His party-switch doesn't bother me at all. I am from Florida and worked on the Charlie Crist gubernatorial campaign last year. Crist was also hammered for switching from Republican to Independent to Democratic, and that is one of the reasons he lost. For those of us who pay attention, however, it is clear that Crist (a moderate Republican) had no place in the GOP after the Tea Party took over, and the same appears true of Chafee.
I'd definitely say Chafee is progressive. There's still a few issues that he's conservative on, but overall he's more liberal than most Democrats. I like him. I voted for him for Governor, and would again. I just can't see him as President or VP.