The Jagiellonian University is unique, architecturally. The Wawel too, but yeah... pretty touristy. St Mary's is very nice. There are a number of great streets off the central square just to walk up and down. If there's a street market while you're there then you'll see all kinds of interesting subjects. Krakow would be a great place to explore rooftop ornamental architecture, if that's your thing. I also found the cemeteries to be very interesting.