Shenandoah Valley-Skyline Drive Classic is a 72 mile loop trail located near Luray, VA and is only recommended for very experienced adventurers. The trail is primarily used for road biking and is accessible year-round.
I know it can be done in a day, but I got a room and made it a two day ride. There are beautiful farms and mountain views along the way. I only have a mountain bike, so that added to the workload.