George Clooney is the obvious choice.
You mean besides the fact he has no qualifications whatsoever?
haha. Okay, you want a serious response. If I were a member of Team Obama, then I'd remind him that this is a once-in-a-lifetime opportunity to name his successor (and stick it to Team Clinton good!)
There are a few choices. Governors usually make for good presidential candidates. O'Malley, Rendell, and Schweitzer all have baggage. As does Webb. How about Cuomo? Or Quinn? Actually, I like Quinn very much. He has the stank of loser on him now, but that may rub off, and anyway after two years as a Vice President it may not matter.
Some thought should go into it because it's a chance to circumvent Hillary Clinton, and that is very important.