St. Martin is an interesting sailing destination and nothing at all like the BVI.

While the BVI tourist infrastructure is centered around charter boats, the one in St. Martin is not. There are few mooring balls, I can only think of the ones out at Tintamarre which are put up by the park service and they are free; but otherwise you will be anchoring every night.
There are some beautiful places to anchor in St. Martin and environs. In Philipsburg, outside the lagoon at Simpson Bay, Marigot and especially Grand Case you have numerous shoreside facilities for wining and dining and shopping. Grand Case is a little less busy and does offer great holding in sand in only 10-15 of water and you can scuba or snorkel at Creole Rock. Anse Marcel is an overnight anchorage with good holding but the wind swirls around a lot.
I have a deep draft boat so don't get into Pinel Island or Orient Beach, but a catamaran or shallower draft can get into there for a nice anchorage. Ile Tintamarre has the aforementioned moorings plus people anchor there. I've stayed overnight in both calm and rolly conditions; much prefer the former. Tintamarre has some good diving and snorkeling and is otherwise uninhabited (see https://www.youtube.com/watch?v=9bKI1Aq8F0s ).
Given enough time, from St. Martin one can zip across to Anguilla and, even better, down to Ile Fourchue and St. Barths. With even more time and calm conditions Saba is also a worthwhile trip.