No suggestions but I pondered that exact trip before booking the Munich/Prague trip that we just took last week.
Incidentally, In Prague, on a beer tour, we met several Germans who wouldn't stop raving about Hamburg though. That surprised me. Never thought about it as a prime tourist destination. Hopefully you find it to be as great as they said it was!
Fun Fact (that I have no way to verify): According to them, there are more bridges in Hamburg than there are in Amsterdam and Venice combined. No idea if it's true, but they were proud of that stat so I thought I'd pass it along.