Rubio was on "Fox & Friends" this morning and came across pretty well. He said he thought the Arizona immigration law was constitutional (that was before the SC ruling was made public). I still think there are other choices that may be better for the ticket, but if he is picked I think he may be able to withstand the media onslaught.
Part of Palin's problem was that her selection was a last-minute decision by McCain, so she didn't have much time to prepare for the media attacks. That won't be true if Rubio is picked.