Leverick Bay Resort on Virgin Gorda might work. Condo's rent for about $1500/1700/wk as I recall. It's quite nice there, good beach, watertoys, on their own little bay - we went there twice but didn't stay there. A few shops/restaurants on property but a bit of a twisty/hilly drive to other restaurants in town and on the south end. You can also take a water taxi to Bitter Creek Yacht Club from there for another dining option. Leverick Bay does a buffet on Friday that most of the tourists and locals attend.
Diving is with Dive BVI, one of the best dive outfits I've ever used. There's no shore diving to speak of on VG though, it's all 15-60 mins. by boat to the best sites. I know DiveBVI picks up at Little Dix Bay Resort($$$), I don't know if they do also at Leverick Bay.
Downside of VG is it's harder to get to, it's by ferry or small commuter plane(Cessna), but it's quiet and peaceful on the island as a result. We couldn't get there and back w/o burning a day in St. Thomas due to flight/ferry schedules, ymmv since you're closer. It should be relatively quiet in August, it was this April which was the tail end of the winter season.
There's good warm water diving, other watersports and a few good restaurants on the island. A big attraction is the Baths, huge rock formations on the south end of the island, great beaches and good snorkeling in the area. Also from either VG or Tortola, you can dive the wreck of the Rhone - I'm not a wreck fan but I enjoyed it. We saw multiple turtles, sharks, lobsters, barracuda and varied reef fish during a week of dives. Not the most prolific fishlife but interesting nonetheless.
http://www.leverickbay.com/
http://www.divebvi.com/
PM if you need more details.
