I spoke with my very good friend who is from Krakow and is an important Polish Diplomat to the U.S.
I specifically asked about Luxury Hotels in Krakow....These are his suggestions:
(not necessarily in order), as he likes all three.
Copernicus
Rubinstein
Pod Roza (Under the Rose). He especially likes the restaurant at this hotel.
I'll be happy to ask him other questions re: Krakow.