We will be in Krakow, specifically - cannot go to any surrounding cities due to time, so please don't suggest that. Besides Auschwitz, which is our reason for going, what are some extra special attractions to visit? Thanks to all!
Castle Wawel. It's in the city. Walk around Glowny Rynek (Main Square), climb the tower for views. Salt mine Wieliczka. We did Auschwitz and salt mine in one day by a tour bus. Costs little more than going independently but saves a lot of time and you have your guide for Auschwitz and also for salt mine. On the way to Auschwitz (called Oswiecim in Polish) you can watch introductory film to concentration camp.
Definitely visit the castle and cathedral, as Ilja suggests. The park along the river is beautiful and relaxing - great for bike riding. The old Jewish quarter is a short tram ride from the city center. The art museum is small but interesting. If any of the milk bars are still operating, stop for a cheap and delicious lunch - perogi russo (camelized onions) are a good choice.
Definitely include the salt mine - it is truly unique. Combining the tours is an excellent way to do it. Krakow was very pleasant when I went. Watch the walls of the old buildings, built with large stone blocks -- you can easily spot big chunks of amber in the rock. This is especially the case around Wawel. If the White Lady mime is around when you're there, let yourself get drawn into her schtick... I have great photos of her and I still smile whenever I look at them.
Some of the churches are quite interesting. Read about why a trumpeter plays from the spire. Like Prague, Vienna and Salzburg, you can also attend a cheap classical music concert.
Just sitting in the square and hanging out at night was great. My husband and I were with our 10 year old and he loved climbing in and out of the hollow head statue. Loved the castle. Loved the pizza in Krakow. My husband thought the women were all beautiful. We took a carriage ride with a (crazy) father and son - something we never do but it was fun! Krakow is a great city to wander in. One morning we walked to the old Jewish neighborhood and then cut through some church and along the river and up to the castle. Saw where the Pope lived. Have fun!
And of course, try the pierogies.