Advice Pre-Krakow Ideas Before Meeting Parents

I'm meeting my parents on a Tuesday in Krakow but am leaving Boston on Thursday night to get there. I have a couple of days to spare before our meet-up and was thinking about exploring somewhere nearby or even stopping over in another city. Does anyone have suggestions for places to visit or things to do before heading to Krakow? I'm open to both city explorations and nature spots, preferably not too far from Krakow. Any hidden gems or must-see places you'd recommend?