Although from the Bush White House, she improbably enjoys national favorbility above 50%. People trust her intentions and qualifications.
The fact that she hasn't run for office is actually a great strength. She can take policy positions that compliment or balance McCain's.
With Rice on the ticket, even more independents will side with McCain (especially those troubled by Rev.Wright). For this reason, Florida would go McCain for sure. Florida also has one of if not the fastest growing black Republican bases in the country (there has been a strong effort by the state party to reach out, and Gov.Crist has been hailed as "Florida's first black governor").The only person who could better secure Florida would be Crist.
Also, she actually does make California seem more realistic. Even if Repubs lose it,they still would have forced the Dems to focus more money and resources in the state.
Lastly, she is black and female. In my opinion, gender and race shouldn't be a factor when deciding qualifications, but the historic significance and electoral possibilities are undeniable. While most people may consider her being black as more of an advantage, it's true that nationwide black support for Obama would barely budge (not including the Florida factor). Her being a woman, however is HUGE, especially given the poll numbers indicating that MANY Clinton supporters would defect from the party and vote McCain if she's not nominated (IF...I ment WHEN).
I liked Mitt before for economic reasons, but he has a lot going against him and I'm now not so sure that his being on the ticket would reassure voters about McCain and the economy; it may actually undermine him by admitting his weakness. In Florida, voters actually trusted McCain more than they did Romney on the economy. I bet your sick of the Florida references, but...
Charlie Crist was my other favorite. With a great ability to unite and as the best retail politician in the nation, independents would eat him up. He gives you Florida. and his green policies and other centrist views would play well in California and other purple states. But that strength may also be his weakness; Conservatives would LOATHE his being on the ticket no doubt.
So in my mind, the choice is clear: Condi's positives would outweigh her negatives and her selection as VP wouldn't substantially upset any of the wings of the party while also appealing to to the center.