Lincoln / Reagan.

I don't see Hilary and Obama coming together. Neither would take the backseat at this point, especially Hillary. She would be a terrible VP pick.

Obama / Richardson would lock up some key votes but two minority candidates?

Clinton / Richardson wouldn't make sense because Hillary already has the latino vote.

I think whoever wins is going to pick the whitest man they can find. Edwards would be the dream VP for both in my opinion but he probably won't do that again. On the other hand he wanted to give the underclass a voice. VP would serve that purpose.