The game against Schalke would be during "Osterwiese", might be a bit more complicated to get a hotel. But "Osterwiese" ends at the 7th of April.
Apart from that I don't know about any big events in April next year so far.
I really don't think that the 'Osterwiese' will have great effects on the hotels in Bremen. I mean 'Freimarkt' OK, but I don't think that people actually travel to Bremen to visit the boring Osterwiese. :grinsen:

and fun than last time with my bad cold...
As I said earlier, those of us who don't make it will just pick another game in the summer months.
Just provide your oldies with enough valerian or sleeping pills. Beer might work as well. Train ride from Hamburg is about an hour, from Luebeck 90 mins, same for Hanover.