Chenango Valley is a great state park. The beach area is well staffed and clean. Changing areas are available as well as a splash pad for the little kids. There are miles of trails to hike and roads to bike.
Oquaga is a great campground if you want to get off-the-grid for a little while. There are plenty of well-marked trails to hike. Bathrooms were clean and well stocked. The staff were very friendly.