Here is an idea I had about a prize that would be awarded for the character that wins. Since pretty much every character in this thing has lost someone they care about in the past, what if the person that wins would get to bring back someone from their past? This way, the prize is the same for them all, and it's something that each person would give their all for.
Now, I can agree with having someone who can judge the matches and debates, a third-party not effected by any outcome.
About locations outside the Marvel Universe: The only rule I would want to see is that it has to be a location that pretty much everyone would be familiar with. We thought about the island from Lost last season, but I think about half the people in our tournament hadn't watched the show. (Another factor that could make a location ok is if you can find a link on the internet that explains it.)