We loved Copenhagen! We spent three days there - 2 before, and one after the cruise and adored every minute. It's a foodies paradise and we had wonderful meals everywhere we went. Nyhavn is not to be missed and worth braving the crowds. We thoroughly enjoyed our meals at M&H and Geranium and would recommend both restaurants enthusiastically.
We opted to stay in Warnemunde and Rostock instead of taking the ship's excursion to Berlin. Rostock was a big surprise as we had low expectations but the architecture and sights were beautiful. The astronomical clock is not to be missed. Warnemunde had the feel of a seaside resort town with lots of restaurants and shops. The beach was beautiful but too cold to swim while we were there.