well, if what i've pieced together about the mc-cain campaign's assessment of the situation is correct, rice would not have worked for two basic reasons---she's way way too closely associated with the bush administration, which would have erased mccain's room to manoever out from under it and position himself as whatever he is trying to position himself as ("a maverick")--and she wouldn't have had anything like the same sort of effect that palin seems to have had on the far right base of the republican party.
on the other hand, rice would not have set into motion what appears to be happening according to aggregated polls not done by television networks, which is to push independents toward obama.
Pollster.com: Omero: The Palin Effect, Preliminary Results
this may or may not end up being meaningful as a result analysis, both because they're polls (the devils in the details) and because it's early in the game yet.
that aside, i would think rice a far better and smarter choice than palin.
but it didn't happen. of the two reasons that i can figure out, i suspect the first was the big one--that and i wonder if rice would have accepted in any event. if i were her, i'd want a vacation.
and if i was ambitious, i wouldn't want to get involved with a ticket likely to loose, particularly one that would be more likely to loose because of me (this loops back to the campaign's assessment of its own situation)