Great State Park
Just a few things to add to the previous well-written reviews, all sites are mostly level and very well shaded. Electric only, there is no water or sewer at the sites. Several water taps are available upon entering the campground, and there are 2 sewer dump sites at the station. There is no wifi in the park itself but wifi is available at the Visitor's Center for the National Seashore just a few miles south.
The park is heavily visited by locals who tended to leave early afternoon, sometimes creating a waiting line at the dump station. For a morning departure the dump station seemed to be open most times.
The park regulations state that no alcohol is allowed within the boundaries of the park. If you practice discretion at your site only and preferably inside of your RV during evening hours it should not be any problem enjoying your favorite beverage.
Take some time to hike the trails. There are several options available from easy short hikes with plenty of shade to much longer strenuous hikes up to 7 miles in length, as well as many options in between. And if you're feeling adventurous hike to the top of one of the 3 talles sand dunes; you'll be rewarded with a terrific view of Lake Michigan.
Take some time to explore the immediate area beyond the State Park that belongs to the National Seashore. There are several interesting historical locations within just a few miles.
We stayed here 3 nights in our travel trailer and would visit again.