One more vote for Francis/Maho Bay (our top 3 anchorage in the USVI/BVI; always plenty of available mooring balls) and Salt Pond Bay (only 5 mooring balls and often full as you get later into the season, but nearby Lameshur Bays have plenty of moorings).

There is good snorkeling along rocks separating Francis and Maho.

Also consider a visit to the Annaberg Plantation ruins. I usually stop on the way from Francis Bay to West End. Tie up in Leinster Bay, dinghy to the small beach, then follow the shoreline trail to the parking lot and short uphill walk to the ruins. Upon your return, you can snorkel around Waterlemon Cay.

If you decide to go to the South shore from Cruz Bay, I suggest a stop at Genti Bay (only 1 public day mooring) to see the Petroglyphs (easy 1 mile walk) and the well preserved 19th century Reef Bay rum factory ruins.