We highly recommend the ATV Tour offered on Jost Van Dyke. It was an easy trip over from Tortola -- a boat picked us up in Soper's Hole, took us for a short ride and dropped us off right near the spot on Jost Van Dyke where the tour started.
Having never been on an ATV before, it was fun (perhaps a bit nerve-wracking?) to learn how to drive the ATVs and our guide was very patient with us. Our group consisted of just the four of us in our family, so the service and schedule was very personalized and flexible. The tour starts at one end of White Bay and takes you up (and I mean UP) one end of the island, across to the other end and back down and over. We had a nice stop at Foxy's Taboo which is a quieter, more tame and "civilized" version of Foxy's. (See blog post...)
The views were incredible and we stopped a few times along the way to soak it all in and take some pictures. At the end of the tour, we enjoyed lunch at One Love Bar and Grill, the price of which is included in the tour price. Also included is the use of the big floating trampoline in the bay (otherwise a small fee for non-ATV Tour participants). We then had a few hours of beach time, giving us the chance to wander down the beach to visit an old favorite, The Soggy Dollar.