I have no objection to Hillary Clinton being VP on policy or even political grounds, save one:
I suspect a lot of other people have the same apprehension that I do - that the Bill Clinton Sideshow will be as damaging to Obama in the general as it's been to Hillary in the primaries. (And it *has* been damaging - it's hard to argue it hasn't.) I don't happen to think that it would be catastrophic in terms of the election, but it certainly could make things more difficult. And then I don't see any way that he'd be willing to stay on the reservation if we won and Hillary was the VP. The thought of Bill Clinton wandering around the executive branch with his own agenda independent of the President's worries me - not because I believe he's some DINO (and to the people pushing that line - you're crazy) but simply because I don't think he'd ever be willing to take no for an answer, and that could be a problem.
This is unfortunate, because Hillary's a very good VP pick otherwise.