Hi
was there about 4 wks ago. There's a Jewish museum in the old Jewish area, 10 mins walk from main square. Worth a look. The square itself is lovely for coffees, beers etc. Pick up a copy of the free Krakow magazine that's in hotels, airports etc. as they have really good unbiased reviews and we tried two restaurants from the mag. Both were excellent and 2 mins off main square. The Salt Mines are about 20 mins away in a bus and take a few hours, all underground so not everyones cup of tea!!
Enjoy
S