Newfun4me...we have done several land based vacations on Cozumel. Sometimes we will rent a car. We always rent from Isadora Isis. It's owned by Maguerite (sp?). She is a very honest business gal. If we do that then we will head to the East side of the Island and maybe go to Punta Sur or just have drive around and enjoy the beautiful wild coast line. But we will also stop at one of the many beach clubs and have something to eat and drink. We will also take our snorkel gear and stop at Playa Corona on the west side, not far from the cruise port and spend the afternoon there snorkeling, eating and maybe a few beers. We also do this when we don't rent a car, since the taxi is so reasonable.
We almost always make a stop at the Mega Mart and pick up hot sauces, vanilla, and anything else that looks interesting. And if I need to re-supply my antibiotics, I can get them here also. They have a pharmacy.
The Mega Mart is like a Walmart. I bought the same vanilla that all of the tourist shops have for $16 for a little over $1.00 usd.