Thompson hasn't really impressed me, now that you mention him. I think he's getting a lot of anticipatory coverage because he's been relatively silent so far.
Once (if?) his campaign gets going, then we'll see.
Oh joy 
Oh yeah, as regards Gravel. He won't get it, unfortunately. I'd most likely vote for Obama. Hillary has the machine, as it were, but I don't think she'd be a great President. McCain hasn't a clue anymore, and Romney is fresh out of positions to take.