Condi isn't running unless she's selected as VP.
Sitting congressmen and senators have a great deal of trouble in getting elected. The last one to do it was JFK, and he needed dead people in Chicago to pull that one off.
So, of the remaining ones on the list, that leaves Rudy, Newt, Frist, and quite possibly Santorum as non-congressional candidates. Of those, I think Newt would be the most formidable candidate.
I wish Jeb Bush was running.
What worries me the most is a McCain/Clinton ticket or vice versa