I think the running mate will depend on how close the election is going to be and who the 'Rat nominee is. If the 'Rat nominee is someone like John Edwards, it makes sense to have Guiliani because he might be able to deliver NY and possibly NJ. If Hitlery is the 'Rat nominee, the running mate will almost certainly be Condi Rice.
I will not be surprised if we see more of a return to the VP spot going to the person who can deliver in the election and then that person being "banished to obscurity" after the election. It is only in fairly recent times that vice presidents really had any duties aside from the Senate and being sent to funerals or other functions that the president didn't want to attend.