Janie,
Speaking only from personal experience, and not having anything in particular to do with Cozumel,
Some ''pay as you play'' hotels are not as inexpensive as they first appear, because every time you turn around , someone is asking for your credit card.
As an example, a few years ago, I paid over $1000. for four of us to have dinner...and it wasn't anything close to lobster/caviar and Dom.
By the end of the trip, when all the credit card receipts were tallied, Sandals, would have been less expensive. Your dives alone at a ''hotel'' could be well over $100 US per outing per person. Where at Sandals, your two tank morning, two tank afternoon and often night dive(s) are all included, as is NITROX.
Up front costs are always better than ''continual extras'' and not necessarily ''more'' expensive.
LOL,
Rose