Krakow is a great place. I really enjoyed it. There are several other location you can visit from Krakow. There is a Salt Mine built in 15-16 century thats about 300 kilometers of tunnels about 100 meters under the ground. There are undeground churches and statues around, quite impressive stuff. Its a must see place. You can also visit Auchschwitz its locatad not far from Krakow.
Bear in mind that night life (as far as i remember) in Poland sucked.