I'm not so certain these two would make for much of a working pair. As the system is designed today, the president and vice-president must remain on the same message. These two gentlemen, while both honorable decent human beings, don't agree on much of anything. For example, they don't agree on (a) the war, (b) abortion, and (c) health care. In case you haven't heard, that's a lot of disagreement. They do agree on certain issues, but that just strengthens their bipartisan creds. Good for them. Seriously. As a Democrat from Texas, I like it when people reach across the aisle to find common cause. But don't confuse a commitment to bipartisan politics with actual agreement on the issues between either the parties or their best candidates.
McCain is a Republican and a damn good one. Obama is a Democrat and a damn good one. They may be able to work together, but I doubt they could do it from the same office. Conservative NYT columnist David Brooks wrote a pretty decent piece today about the different styles of leadership between these two individuals. I don't agree with all of it, but I still recommend that you read it.
At the end of the day, it's AMAZING how giddy we all are about potentially electing two people whose principal claim to fame is not indulging in the infantile partisan hackery that has infected our government on every single level. That's no criticism of McCain or Obama. It's criticism of the rest. A willingness to engage the opposition should be part of STEP ONE in judging whether a candidate is appropriate for holding office. If we elect both of these gentlemen to the heads of their respective parties, we will have taught our reps in Washington that very lesson.