Caneel can be rolly, but if you're in a cat, no worries.
Maho / Francis bay has a huge mooring field. Good Snorkeling in Little Maho I hear.
Leinster Bay is also very nice.
Trunk Bay has day moorings and you can dingy in to a calm beach and even snorkel the underwater snorkel trail from the beach.
all of these are short on facilities and long on views and "remote feel" ambience.