This is probably one of my favorite campgrounds in PA and we like to stay right along the wooded area by beach and playground.
This gives the kids access to water, playground, and a quick trip up to the camp store for ice cream. We've also rented a pontoon boat for the day from the marina which is great time as well. They have a mountain bike course in the back of the park in addition to hiking trails that border the lake.
Prince Gallitzin is definitely one of the larger state parks in Pennsylvania so expect there to be a lot of people and busier but it's a very nice place to visit.