What about executive experience?
Former governors usually make better managers which the President is of course. Congress critters just don't as a rule. (shudder at the thought of Kerry, Edwards etc. in the Oval Office).
This is aside from their political beliefs.
Hillary, Obama, Edwards, McCain, Thompson - no executive exerience.
Rudy and Romney - extensive executive experience (Rudy as Mayor and consultant, Romney as money-manager, Olympics director, and Governor of MA).
Richardson (dark horse, no pun intended) also has executive experience (Sec of Energy, Governor of NM).
If Fred Thompson had Rudy (particularly) or Romney's executive experience, that would make for a great candidate (and President).