I just got back from the Iberostar Grand and that hotel is awesome. I did not dive that trip because my experience has not been a great one after diving Cozumel so much so just stay dry and enjoy the hotel. It is a beautiful hotel and very 5 star. Let me mention lobster being grilled on the lunch buffet! The indoor pool and jacuzzi are nice in the winter if you come in cold...some warm water to take the chill off. Butler service is at the pool, the beach, and a phone call away.
Dont forget to tour the restrooms on the property...they are even a work of art! Oh and the artwork there is between Europe and Las Vegas! Good choice on the hotel. The dive shop is located at the Iberostar Beach ... it is a ways down so lugging gear wont be good. They can take you by golf cart to the lobby of the hotel at least. It is the farthest hotel from the Grand so its a walk down to the dive shop which is on the beach of course. Saw the boat and it looked good and it had quiet a few divers on it one day I was walking by, Have fun !