Berlin is so fucking cool, definitely go there and walk around downtown. The eastern part of the city has a lot of Ostalgia so there's no shortage of socialist swag you can see and get, I remember the German part of my family when I visited took me to a revolution themed cafe after learning I was a socialist, it was pretty neat.

Most of Germany is like the Midwest though - long rolling hills, small towns scattered around, local truck stops with kitschy flavor. If you're going to multiple places, I recommend renting a fast car and driving on the Autobahn, it will make you hate other highways even more for not being nearly as well maintained. The biggest difference between this part of Germany and the US equivalent is the massive amount of history - if you like castles, then by god Germany has some badass castles to go look at.

During my trip we had six (!!!) kids with us, so a big part of my experience was going to public parks and playgrounds with them. If you can take an American kid with you to one of those you will forever ruin American playgrounds for them, because the German ones are well funded and not nearly as constrained by safety concerns.