If you look at a map, you can see what cities lie sort of in between Berlin and Munich. Leipzig and Dresden have already been mentioned, but you might want to check out some of the other cities. What about Erfurt?
Most of Germany isn't well known for their hockey teams, though big cities are going to have teams, smaller cities probably won't.
Every city is going to have its' own history, so whether you are looking for stuff about Celts, Romans, Neanderthals, Holy Roman Empire, Tribes (Alemanians, Chatten, etc.) Franks, Prussian, Religious, Teutonic Order of Knights, Jewish cultural sites, 30 Year War, WWI or WWII, Cold War, etc. you are going to find something almost everywhere you look. Depends on how much of each you want to see.