Barbara and I like the Fiesta Americana. You can dive with the Dive House--which is right on site and has lockers right next to the rinse tank and dock--or other dive houses very conveniently.
Why we like the Fiesta:
(1) Dock is on site--the Dive House boats and all other dive shops will pick you in a most convenient fashion.
(2) The breakfasts are good and the restaurant is very near the dock--so, if that is your pleasure, you can eat breakfast, stop by your locker to get your gear, and walk to the boat.
(3) It is away from the bustle of town, but only a $4.50 taxi ride into town.
(4) Great pool and good restaurants.
(5) Big, comfortable rooms with nice balconies overlooking the water/beach.
(6) Reasonable room rates--and, if you like, you can arrange for a dive package with Island Dreams, a very reputable dive travel specialist out of Houston.
(8) Excellent staff--fully bilingual and very, very helpful.
(9) Since it is more southerly than most other "resorts", the boat rides to the dive sites are shorter.
But, wherever you stay, you will love Cozumel--wonderful diving and people! And do not forget to try the French Quarter for a great meal--it is located in town. Finally, try to fly into Cozumel directly--there are direct flights from Houston. We have done the route thru Cancun and it, to use a modern phrase, SUCKS: Aero Caribe frequently delays or cancels flights until a nearly full aircraft can depart; this can mean delays up to six hours sometimes!
Again, enjoy Cozumel!
Joewr