I've snorkeled at the beach by the Villas. Yes, the beach there definitely is better than the Westin hotel's and less crowded than the Sheraton's. And it's easier access and shallower than swimming out to Black Rock. (Perhaps significant for novices, weak swimmers, or young kids.) While it may be a great beach, I would not say that it is great snorkeling. There is a reef there, but snorkeling at Black Rock is much better.

We did a couple scuba dives at Black Rock, too. A gentle drift dive from the north side of the rock to the south side one day and a night dive one evening. You don't have to stay at the Sheraton to have access to Black Rock. And you can park for free when visiting the beach near the Villas. And there's a park area by the beach on the south side of the Villas with a covered building with picnic tables.