If you happen to be interested in or open to a smaller city between Berlin and Munich that is off the typical US tourist radar but on the typical German tourist radar, Erfurt is a great city. It has its own Oktoberfest that is quite different from the one in Munich -- smaller, only one beer tent, more family oriented. It is scheduled for Sept 25 to Oct 11. https://www.erfurt-tourismus.de/veranstaltungen/hoehepunkte/erfurter-oktoberfest-2026/
An excellent hotel in Erfurt is Hotel Domizil. It is located just off Dom Platz, the square where Oktoberfest happens. The hotel is run by a mother/son team. The son is a chef. Breakfast is very impressive. Rooms are clean. I had one of the "Dom-view" rooms during Oktoberfest and would sit in my room at night with the window open, listening to the music and singing emanating from the beer tent. It was quite pleasant.
Erfurt has Luther sites, a gorgeous old town that was largely spared Allied bombing during WWII, a rather impressive Merchant's Bridge, a medieval synagogue, a former medieval Jewish bath house, Anger One (a former Jewish department store "Aryanized" by the Nazis, then taken over by the Communists, and then transformed into a modern shopping complex), and a former Stasi remand prison turned into a museum.
There is a very, very interesting museum at the site of the former Topf und Söhne (Topf and Sons) industrial complex (only a former administrative building remains). Topf und Söhne was a conglomerate that made many products, including the ovens for Auschwitz. The museum explores how a "normal" company with "normal" owners that shielded Jewish and Communist workers from the Nazis became heavily involved in genocide.
You'll notice Willy-Brandt-Platz just outside the train station. Willy Brandt was the first West German Chancellor to visit East Germany, and Erfurt was the site of his visit. The East German government was embarrassed because so many East Germans showed up to cheer Brandt and who shouted, "Willy! Willy! Willy!" to try to get him to make an appearance in front of the crowd. Brandt gave the crowd a small wave of acknowledgement from the window of the Hotel Erfurter Hof, now offices/apartments at Willy Brandt Platz 1.
Of note, Erfurt was named a UNESCO World Heritage Site in 2023 for its Jewish-Medieval Heritage including the Old Synagogue, the ritual bathhouse, and a preserved medieval residential building.
Weimar and Eisenach are good day trips.