It definitely is worth spending some time in Krakow to just walk around the old city/ Jewish quarter, go to bars and restaurants, and just enjoy the ambience. It's a really cool city that feels to also be just hitting its stride with trendy cool places. Maybe if you're from somewhere else in Europe the prospect of walking around an old city doesn't excite you as much, but to me I'm still totally captivated. Krakow is one of the best preserved cities from before WW2 and you could spend a whole day just wandering around nice alleys in the old city and hunting down small pierogi places on quiet corners.
Having Auschwitz be one of the main tourist attractions there is such a surreal, almost funny thing. I remember hanging out in hostels at night, getting plastered on cheap beer on long beautiful summer nights with people from all over, and the conversation always being about Auschwitz---which is real heavy as far new-hostel-friends-flirting vibes goes. To be honest, going to a Jewish school all my life probably made the whole thing... easier? for me to process than for everyone else. If that makes sense. I probably would feel a bit icky going to a plasticky park like Energylandia after, but there really is no reason to feel guilty about it at all. Everyone else is going back to their hostels/hotels and getting plastered, so...
All up, I really adored my time there. Energylandia is not bad too! But I can't say anyone else at the hostel fathomed spending a day there...