These places have very nice web-sites, but before you click on their links you should consider: a minimum of seven days to visit St. Thomas, 14 days for St. Thomas and St. Croix, don't forget we are going from P.R. and coming back to P.R.
If you don't have seven days  the best plan  should include P.R. south shore only.

Puerto Rico is a beautiful place, if you  prefer to combine sailing with some drive sight seeing, you should reserve at least five days for driving around. No habla español? no problemo.

U.S. Virgin Islands: Other than a bit crowded (and that is only in Charlotte Amalie) I can't think of anything wrong with it. Good for shopping , no tax.

British Virgin Islands: Similar to the U.S.V.I. but they talk funny (english accent). One visit to Customs should take care of everything, passport required for non-british visitors.

You have to remember that everything in the V.I. is imported, even the water!