Options for 3 days post RS Poland tour

There are a few points of interest in and around Krakow that are worth seeing that I can suggest (don't think they are in the RS tour), some work better as multiday side trips and some are good for day trips:

Polish Aviation Museum in Krakow: has well preserved airplanes from WWI, WWII, and the Cold War. Including Hermann Göring's personal WWI airplane collection and Pope John Paul II's Papal Helicopter, located on the outskirts of Krakow (can take a taxi). I was there over last summer had most of the place to myself.

Czartoryski Art Museum in Krakow: home of the famous Leonardo da Vinci's Lady with an Ermine painting.

Zakopane: Mountain resort town with plenty of outdoors activities like hiking in the summer and skiing in the winter.

Trail of the Eagle's Nest Castles" a string of 25 medieval castles and fortresses as a bulwark against the encroaching Kingdom of Bohemia. The castles are located in a protected area called the Polish Jurassic Highlands, a hilly landscape of Jurassic limestone cliffs and valleys, dotted with many charming villages and dense forests. This is a daytrip not many foreigners know about but is probably the best daytrip from Krakow if you want to see castles. I visited them driving with a rental car back in 2019, here is my trip report - https://community.ricksteves.com/travel-forum/trip-reports/new-daytrip-from-krakow-eagle-s-nest-castle-trail

Pszczyna, an ancient market town and former capital of the Duchy of Pless in German or Pszczyna in Polish. Another nice daytrip from Krakow. The main attraction is the Pszczyna Castle (https://www.inyourpocket.com/katowice/pszczyna-castle_155752v), also known as Schloss Pleß. Once the residence of local German dukes, it is a fine example of baroque architecture and is surrounded by a beautiful English-style park. Inside, the castle offers perfectly preserved 18th and 19th century interiors including original furniture and artifacts, a rarity to survive both WWI and WWII. There is also a Silesian ethnographic museum and European Bison reserve close by.

Wroclaw, my favorite city in Poland! At various times, Wroclaw has been part of the Kingdom of Poland, Bohemia, the Habsburg Monarchy, the Kingdom of Prussia, the German Empire, and finally back to Poland after WWII. The architectural eye candy around the old center reflects this unique history, as it incorporates a little of every country that has ruled the city - from Polish Gothic to Austrian Baroque and German Modernist. Both the local cuisine and culture reflect this multi-layered history too. Every time I get back to Wroclaw I always discover something new and interesting to experience. Here is one of my trip reports (with photos) of the area - https://community.ricksteves.com/travel-forum/general-europe/vicarious-travel-poland-2017-wroclaw-silesia

Katowice, once heavily industrialized during the Communist times, the city has transformed into a modern cultural hub in the last decade. The city's new era is symbolized by the Silesian Museum (https://www.inyourpocket.com/katowice/silesian-museum_137651v), a brand-new state of the art museum built atop the former coal mines. Above ground, you'll find sleek modern glass buildings, but the main exhibitions are found underground, preserving the memory of the mine. The museum showcases a wide variety of exhibits, including art, historical artifacts, and multimedia installations detailing the history of the region.

Zakopane isn't a hidden gem, but its where I'd head. It's a mountain resort town. There're probably tour buses that depart from Krakow.

The Schindler Factory Museum was well presented. A few days later, quite by accident, my son and I ended up wandering around what used to be the camp for the Schindler workers. It would have been nice to visit that sight with a guide.

Thank you, fantastic suggestions!

I do think a day trip to Auschwitz is a good recommendation. It does take all day and you may not want to do a lot that evening.
I really enjoyed the museum located under their market hall. Had no idea how huge it would be or how interesting. All text was in English. That easily uses a few hours. Strolled around a lot, went up to the cathedral, sat and people watched, shopped for the perfect shawl, explored Kazimierz extensively. This old Jewish quarter had 7 synagogues and I think I was able to visit 3 of them. Had very delicious meals over there.