Getting there from the Virgin Islands is easy--it's all downwind. Coming back may be a bit more interesting, depending on how hard it's blowing. We saw whales breaching in the Virgin Passage when we went almost three years ago.
Imagine3frolic's suggestion of Culebra as a place to start is a good one. Anchor in Ensenada Honda near the town of Dewey. Other pleasant anchorages are Dakity and Bahia de Almodovar, our favorite. Both have free moorings. Be sure to go over to Culebrita--a spectacular beach and good hiking. Vieques has some really nice anchorages, too. It's very isolated on the western end, where the US Navy used to conduct bombing practice. You can still see the old bombed out tanks and trucks on the hillsides. Don Street's guide has good directions for getting in and out of the sometimes trickier anchorages.
The Spanish Virgins are well worth seeing, and a welcome break from the busy USVI and BVI. Services are limited--you have to lug water and diesel in jerry jugs. On weekends, power boats arrive from Puerto Rico (Street calls them the "Puerto Rican Navy"), so get your mooring or anchoring spot early on a Saturday. When you get to Culebra, you will need to clear in. Try to do it over the phone. I tried walking out to the Customs office in the airport on Culebra, but no one was there--it's only open on an erratic schedule. When you call, they may require you and your crew to come in in person.