My son and his friends are Going to Eastern Europe this summer...many of the he cities you mention. Where do you recommend They go?
If they go to Krakow, the Wieliczka Salt Mine is a must. Of course we also did the tour of Auschwitz. In Budapest, do the nighttime Danube cruise when they light up all the buildings.
If they are into history, we did a tour in Warsaw with “Adventure Warsaw” that will take you to a lot of places in the city “off the beaten path”, even had lunch in a “Milk Bar”. A lot of people don’t particularly care for Warsaw, but I was fascinated with the city because of all the history, and it’s changing constantly. Probably the best thing to do in Warsaw outside of Stare Miasto, is the Uprising Museum.
We also did Cesky Krumlov, but it was just for a few hours, wish we had more time there to explore.