Splitting a hotel in Frankfurt would be very nice. From experience, you don't really need to show up before noon and still have a good chance to get great spots. Though, of course, that could always be different. Hannover isn't that far from Holland, and should they get no shows there might be quite a few coming over. And Dutch fans are much crazier than lazy Germans.
Still, there is trains running very early from Berlin, so that might be an option. I just would be happy about some dates, also since I might be going to Vienna and then I need to know things for certain.
Is Tracey coming?
Otherwise, I don't have the last clue about my situation about a year from now, but when U2 is playing I'm all in.
When it comes to sightseeing, Frankfurt is a bit interesting, Hannover way less, and Berlin is the place to be.