If you can only fit one cavern into your Shenandoah itinerary, head 25 miles south from Front Royal to the world-class Luray Caverns and hear the 'Stalacpipe Organ' – hyped as the largest musical instrument on earth. Tours can feel like a cattle call on busy weekends, but the stunning underground formations make up for all the elbow-bumping. To save time at the entrance, buy your ticket online ahead of time, then join the entry line.
Also here is a Ropes Adventure Park (adult/child $11/6) and a Garden Maze ($10/6).