Aha! I plan on doing something of the same myself, next spring.
If you haven't seen the German version of Tanz der Vampire, do it.

I do believe it is playing in Berlin, at least, and usually one or two other places.
I also know that the world premiere of Rocky is happening in Hamburg this coming November. Between Drew and Wietske you're guaranteed some strong performances.
Ordinarily I would strongly recommend a visit to Vienna to see a production of the VBW, as they do a truly magnificent job there. Starting this fall, they are running a revival of Elisabeth (which is truly magnificent) in the Raimund Theater, and Legally Blonde (ymmv) in the Ronacher.
Also, I don't know about the other cities but Vienna does have a "summer pause", so be sure that shows are playing when you schedule your visit.