Help With Trip to Germany PLEASE!

I am joining my husband for a business trip to Nuremberg, after which we will have a few days to do what we want. Last year, we traveled to Munich, Salzburg, Fussen and Prague. All of which we thoroughly enjoyed. We visited churches, palaces, and the Neuschwanstein castle which were all amazing. The architecture in Munich and Prague was so beautiful. I only get three days to explore this year. I've considered spending 3 days in Berlin or going to Mainse for wine tasting (Something my husband enjoys), visiting the monastery in Bonn, and then heading to Cologne. There are so many choices, and I need to decide; 3 days is not enough! What would you do?