Can anyone recommend any nice places to spend some time outside of Krakow (within a few hours travel)?
Sanok, which is an excellent base for exploring the Bieszczady region. You can visit charming towns from there such as Cisna and Ustrzyki Dolne, and Sanok itself is a wonderful little town. Depending on your preferences, you might want to spend a couple of days going round the so-called Bieszczady Loop via Ustrzyki Górne, or you might want to base yourself in Sanok and make daytrips from there.
Public transport in summer in Bieszczady is excellent.
Here's the public transport timetable from Kraków to Sanok.