Amazingly, we had so much fun with our DD7 and DS15 at PI that we went back. There are plenty who will say it's not appropriate for kids, but our trick was to go early.
DD7 especially loved the Comedy Club, which is family friendly in the earlier sets. We went to one set, then went right back in for the next. She still talks about it.
The Adventurer's Club does a good job with the Junior Set in the early hours.
And my DD and DH had a magical dance together--in the Disco Hall I think (LOL); granted it was so early they were the only ones on the floor. It was a wonderful evening.
Please don't light the flames--PI should belong to adults after 9 pm. And ones younger than me after 11. But the early hours are family-friendly, and the adult partiers haven't even started to wind up.