We went to the Jellystone near Hagerstown. Tried it twice and had problems both times and will not go back. The Hagerstown KOA gets reviews with reports of difficult roads to access including drop offs at the side of the entrance road. We have been looking for alternatives in this area and it seems like it is necessary to go further away for a decent campground - Harpers Ferry or even Winchester. Or for Frederick go to Gettysburg where there are a number of campgrounds and make the drive down and back to Frederick.