How about a foreign policy powerhouse, and announce in advance that they will be Secretary of State?
With Cain’s health concern, it should be someone presently Presidential with gravitas, not a Palin, Ryan, Rubio, or Bachmann. Newt’s not a bad call. DeMint is on the Senate Foreign Relations Committee, so would fill that bill.
I can think of a lot of good reasons not to pick Condi Rice, but her name comes to mind.
I don’t think anyone will go near Newt, not even for the cabinet.
Though I don't think Newt would be a great complement to the ticket, I would LOVE to see him "debate" Biden...