FWIW: We bought, moved onto our boat in BVI in Sept 2014 (Tortola). Stayed in the BVI then went West to St. John, St. Thomas, Puerto Rico
until Jan 2015. Then back to St. Thomas and into BVI again in March 2015. Then St. Martin for a month and then down the islands towards Grenada
. So, I've lived in all those places aboard our catamaran
. We've seen a great many charterers in all places.
Just some thoughts being there and not having an agenda:
1. BVI is incredibly safe. We never once locked a dinghy
until we got to St. Martin where every day on the radio
net there were warnings of dinghy
thefts. I really enjoyed that feeling in BVI of safety
since we have kids
2. St. Marten/Sint Maarten has a lot to offer but we did not enjoy the Simpson's Bay experience. If you charter get out and go somewhere. Orient Bay is a water
sports paradise. Lots of clean water up north there.
3. Take your time. Try not to have an agenda and just enjoy the time wherever you are at the moment.
If I had only a couple weeks I would go to BVI. I would go across to St. John. We have not seen cleaner, clearer, more aquatic life outside BVI and St. Thomas/St. John. and going between the two is trivial. St. Martin is rougher water and less choices for calm anchoring/mooring and much less safer when it comes to petty crimes. We never had any crimes against us but when in St. Marten that's all we heard about. Every dinghy is locked and everyone is on guard, boats locked up when unattended and boaters weary of being boarded at night or when they are away. Sad really as St. Martin is a nice place in many places. Just the French side that had all the potential had the most issues which was not so nice.
Either way you decide you will enjoy it although I suspect you will be more relaxed in the BVI or USVI.