It is a memorial rather than a tourist attraction and visiting it is always traumatic.
Excellent point. After visiting Majdanek I was extremely depressed for a day or two (very unusual for me). I do not regret going, as we should all remember what happened in these places, but I'm glad I didn't visit during a holiday.
Wieliczka is a must-see, no doubt about it. I can't say I like the salt for food, but the mine is astounding.