We lived in Germany for four years and I lived in the Middle East for five years. Also, we have traveled many times to Europe since I retired in 2010.
I love all the places that you desire to visit. My Wife and I were married near Copenhagen. We went back there in 2014 for two cruises and spend five days there. The people are great and there are interesting things to see, especially going to the Viking Museum outside of the city.
Also, Dubrovnik was great, but we pretty much did the city in one day. I am not sure why you are spending four days there. Are there other places outside of the city to see?
Prague is a great city, but again it doesn't take four days to see the city.
From my personal point of view, is to see as much of the World as I can. I have been to 70 countries and still have about another 15 more that I want to see. Yes, I have been back to some of my favorite places, but my focus is on seeing the World.
These cities are great, but still not my favorite places, even in Europe. I suggest broadening your scope of travel as well as trying to concentrate your visits to places not so far apart. Constantly traveling between cities reduces the opportunity to enjoy where you visit and flying takes up a lot of time. Munich has a lot to see (consider the Romantic Road in Germany) as well as nearby Salzburg and Vienna, Austria and Garmisch and Fussen, Germany. You can easily connect with Prague and even Berlin or Nuremberg. If you like Croatia a lot, Split and Trogir north of Dubrovnik are worth a visit.
