Pike Lake is a local favorite, with decent hiking trails and beach. Heed warnings of swimmers itch and know that the dog beach is very small, with no beach at all (just a place rest for your dog to go take a swim.)
As for the campground, it’s small and has relatively little privacy so you’ll make quick friends with your neighbors - unexpected from a state park. But the restroom facilities have flush toilets & showers, and are clean.
Be sure to check out the interpretive astronomy trail and take the walk up Powder Hill to the tower!