Two Polish Cities

I think Krakow has to be one of the cities. It has a more refined and polite
vibe than Warsaw, imo, and since it is the closest major city to Auschwitz,
definitely a place you'd probably stop in anyways.

In addition to Auschwitz, the Wielizcka Salt Mine is nearby and pretty cool.
Also, Oskar Schindler's factory.

Wow, ask me to pick my favorite child, too! We liked Wroclaw quite a bit, but to pick two, it would have to be Krakow and Gdansk. Krakow reminded me a bit of Prague, and there is a lot to do there. Gdansk has different qualities. Gdansk was one of the hanseatic league cities and the buildings reflect that. The WWII museum and the solidarity center are must see. The old town area and the area along the river are quite picturesque. Both Gdansk and Krakow have many day trip options.

In Krakow, there's the castle, the Jewish area, many beautiful churches, the Schindler museum and the huge and lovely old town.

Two additional cities I really enjoyed were Torun and Bydgoszcz, but both are out of what I'd consider day trip range.

Gdansk and Krakow are quite a distance from each other. Some might suggest picking one of the two and Warsaw to reduce travel time. Auschwitz is an easy day trip from Krakow, so doing Krakow and Warsaw might be a good choice, logistically. We didn't enjoy Warsaw nearly as much as the other three on your list. It is a lively city with a lot of history, but most everyplace is new, being almost completely decimated during WWII. It also is quite a large city, and we tend to enjoy places a bit smaller.

Although Wroclaw is my favorite city in Poland, I think for a first time trip the best would be to combine Warsaw and Krakow, since you want to visit Auschwitz too. Krakow and Warsaw are pretty well connected with a high speed train. Warsaw represents modern Poland, while Krakow showcases medieval Poland.

Both have pretty good day trips too. For Warsaw you can day trip to Torun and Kazimierz Dolny.

From Krakow you have more options, in addition to Auschwitz, you can also visit the Tatra mountains via the spa town of Zakopane. You can also rent a car and do a drive visiting the trail of the eagles nest castles, a string of fortifications in various states of preservation around the Krakow area to protect it from the Czechs.

I made a day trip to the eagles nest castles trail a few years ago here is my report - https://community.ricksteves.com/travel-forum/trip-reports/new-daytrip-from-krakow-eagle-s-nest-castle-trail

It's looking like a high-speed train runs from Gdansk to Kracow, about 5 hours duration. So that should also work. Looking like those might be our two cities. Warsaw seems to be less charming and more frenetic than Gdansk.

Warsaw seems to be less charming and more frenetic than Gdansk.

Really depends on what you're interested in, I'd say both Krakow and and Gdansk are good for medieval history, honestly they overlap in a lot of things.

Warsaw is better for 20th century like World War II and Communist era history.

Warsaw seems to be less charming and more frenetic than Gdansk.

Gdansk and Krakow are great for their touristic sites, old towns, etc. But if you're visiting to gain insight into Poland and the Polish people, then I think you really need to see Warsaw to fully appreciate the country - especially its resilience following an extended traumatic period under Nazi Germany and then Stalin.

Warsaw is fast-paced, but the food scene is interesting - you can go for days without eating traditional Polish cuisine. The Soviet Palace of Science and Culture rivals Rome's Vittorio Emanuele Monument for over-the-top flamboyance. World-class mass transit.

I found that Gdansk had more "personality" than Krakow, even though Gdansk has been rebuilt and Krakow is original. And the food scene in Krakow is amazing - with just about every culinary ethnicity represented. Be sure to spend time in Kazimierz - for the food and the atmosphere.

Malbork Castle is an easy day trip from Gdansk.

There's not a bad decision to be made here. Just be aware that Gdansk and Krakow are both very, very touristy. Warsaw is big, but most of the people you'll see will be locals. The tourists are typically confined to the small, rebuilt historic center.

,,, Wroclaw is my favorite city in Poland,

I had a very enjoyable 4-night stay in Wroclaw. Great city for walking around and just hanging out. All highlighted by the Town Hall and Market Square as two of many highlights.