Smartest choice is Ayotte. She'll bring in NH, help with women and younger voters.
Remember, the McCain states plus NC, FL, VA, IN, OH, and NH = 270 EVs.
Picking a relatively young, freshwoman Senator with less than two years in office will inevitably led the voters to one conclusion: Sarah Palin 2.0.
Of course, Ayotte is not Sarah Palin (as much as I disagree with her politically, she's a smart one and relatively accomplished during her career), but most of the voters won't even know who the feck she is. All they would know are: woman, young, recently elected... just like Palin.
Picking Palin for Vice Presidential nominee was a huge setback for the Republican women in politics.
Romney is not stupid to repeat McCain's mistakes (he's good in making mistakes on his own
). Looks like the smartest thing he can do is to pick some boring, white dude indeed.