Lisa, did you happen to see the recent discussion about spending an entire day going to and returning from Auschwitz with no overnight in Poland? OK, Europe has countries smaller than the United States. But would you recommend someone attending a wedding in San Diego to visit Portland, Oregon on the same trip?
Poland does not pair well with even adjacent countries. Cesky Krumlov is quite a remote location. When we were in Prague for five nights, we hired Rick‘s recommended car service to drive us three hours to CK, and three hours back, same day.
CK is worth the effort to get to, but I suggest you put it off to another trip. It’s fine to spend the night, but that is not necessary.
https://community.ricksteves.com/travel-forum/czech/prague-to-auschwitz-in-1-day