I think Clinton has a stronger incentive to pick Obama as VP than Obama has to pick Clinton. He would add his supporters, his air of bipartisan compromise (which is my least favorite thing about him, to be honest), and his message of change to her message of competence and experience. I don't see how a Clinton/Obama ticket could lose, especially against a McCain/Huckabee ticket, with its combination of old angry guy and squirrel-eating nutjob. If Clinton doesn't pick Obama as VP, I think she still stands a good chance of winning, though the race becomes a bit harder.
Obama, on the other hand, has little to gain by picking Clinton as his VP. I see him going for Jim Webb, or maybe Kathleen Sebelius, either of which would reinforce his message of getting new blood into Washington.
As for myself, I agree with Woody: the two families passing the Presidency back and forth like that for over a quarter of a century smells a bit too strongly of the Plantagenets during the Wars of the Roses. That's what's pushed me over into the Obama camp for now. Still, if Clinton wins the nomination, I'd vote (and campaign) for her enthusiastically, and not just because McCain scares the living daylights out of me. She may not be perfect (far from it, in fact), but she's a smart, capable, hard-working American with a firm grasp on the issues facing the country. Sounds like good Presidential material to me.