Do not pick up someone just to pick someone up. If you have a spot on your bench that is going to just be used as a bench spot, then do one of two things. I am assuming that you want a pitcher.
Is your closer situation solid? You might want to pick up a set-up man that would get the closer's job if the closer gets hurt. Such as Rodrigez from the Giants, Levine of the Angels, Karsay of the Yankees, etc.
OR, you might want to grab a pitcher that is currently in the minors, but should make it to the big leagues shortly. Obvioulsy Prior is probably gone. How about Brett Myers, Peavy, Tankersley(already up, not sure how long). Do some research and see which teams have some injuries and might call up one of their stud prospects.
If you don't like either suggestion. In reality, all of those pitchers are on about the same playing field. Hampton might be ok away from Coors, Stephenson is a huge injury risk, Anderson might be your best bet b/c his team wins alot of games and scores runs. Your Florida pitchers probably won't see much time once eveyone is healthy. Good luck!