If you would prefer to explore the area a little East Harbor State Park is nice. They only have a few full hook up sites and they go quickly. They have several electric sites and a places to get water and a dump station, if full hookup is not a must. The campground has a beach, a little nature center, planned activities for kids, and is peaceful. Marble head has a cute lighthouse that is free to climb (great view of Cedar Point), I am pretty sure you can take the jet express from Sandusky over to Put-in-Bay and maybe even one of the other islands in Lake Erie. Put-in-Bay is fun to explore. I would stay at Cedar Point campground for ease of access and early entry if that is all you want to do, but if you prefer a campground that you could get to Cedar Point from and do other things East Harbor is great.