My wife and I took a recent trip to the US virgin islands and visited St. Thomas and St. Johns. Visited lots of beaches on the trip. We both wore a thongs nearly 95% of the time when on the beach. We typically avoid the crowded areas of beaches as I want as much quiet as possible and didn’t have any problems or comments from anyone. Plenty of people saw both of us walking around on the beach, sun bathing, snorkeling and in the water in thongs and never had a problem.
My wife wears mostly skinzwear and I wear my own. I made my own patterns which are basically a copy of the prior dore/beachndance before the owner passed away. In my opinion the dore ones were the best ones I every owned.
St. Johns: Trunk Bay, Cinnamon Beach, Hansen Bay.
One note about the ferry back to St. Thomas late in the day. Make sure you get there 1 hour before the ferry time to get a spot. There was a long line when we tried to travel back. Next time I would visit St. Johns I would stay on this island for a few days.
St. Thomas:
Magen’s Bay: At the far end of the beach. Lots of Pelican’s fishing and saw 6 baby sharks in the water. Lots of locals were walking up and down the beach.
Neltjeberg Beach: This was a drive down a switchback road. We did this easily in a jeep we rented. Parking is close to the beach but not too many spots available. Visited this beach twice and it was not crowded at all.
Santa Maria Beach: This is a 20 - 30 min hike, there is not many spots to park near the road. The entry is near a double gate that was locked. Its wide enough for a car but I wouldn’t recommend driving your car down the path if it was unlocked.
Stumpy bay:
To visit this beach I would suggest a Jeep with 4x4. There is an abandoned car about 1/2 way down the road that we parked. The road beyond that is not passable with a jeep IMO. There was no one here when we visited.