Hi, Krakow is awesome, Make sure you see the Jewish district & visit ausctwitz, its a harrowing day out but well worth visiting, by night the place is getting quite cool & trendy, i recommend comming away from the market square & trying some of the smaller more local bars, the prices are cheaper & its great to make conversation with the locals in a quieter environment.
We stay at the dizzy daisy hostel, its not flash but its clean, comfy & 5 mins from the market square where everything is centred, have fun, im going back in November to visit the awesome market