Lets assume for the sake of argument that John McCain was looking for the following traits in a vice-president:
--Acceptable to the conservative base
--Doesn't automatically alienate swing voters
--Seen as ready to be president if necessary (experience, etc.)
Now lets look at the candidates and see how they fare:
Carly Fiorina: She does seem like Mitt Romney in a pantsuit. But had McCain picked her, the press would have instantly focused on her departure from Hewlett-Packard. She has no governing experience, so the heartbeat questions would still be there. Conservatives would view her warily. She has been one of McCain's surrogates, but hasn't done such a terrific job that her campaign skills would stand out. If McCain is trying to avoid being the ticket of the rich, a CEO is your last choice for vice-president.
Meg Whitman: The conservative base would probably find Whitman to be acceptable. The scale of acceptance probably does something like: hatred, suspicion, lukewarm, acceptable, happy, ecstatic. Her eBay time was largely a success. Again, the heartbeat questions are going to be even louder for her than they were for Palin. And she does pose the problem of being one of the few people in this country who is richer than McCain's family.
Lisa Murkowski, Olympia Snowe, Susan Collins: No, no, no.
Liddy Dole: She's running for re-election, so picking her could cost the GOP a Senate seat. She has no ability to campaign off the cuff and was very wooden in her run for president. If she was 10 years younger, she would have been a more serious prospect.
Kay Bailey Hutchison: This is probably the only other really viable candidate. The base would veer between hatred and lukewarm on her selection. She is a good campaigner, but not one that excites voters. In some ways, she is a female John McCain: fairly solid conservative who crosses over just enough to give the party heartburn. The experience questions would be less likely to come up.
No one can deny that Sarah Palin added excitement to the ticket unlike any other. If McCain wanted to simultaneously make the base deliriously happy, enrage the other side and make swing voters go, "Hmmm," he could not have picked a better candidate. Peggy Noonan (among others) is right: this pick is dynamite. We just don't know if it is going to blow up on Obama or McCain.