There is a dive shop on every corner and several of them A1. I sent you a PM with my thoughts on that. The dive sites I feel free to share as I think everyone can benefit from this information. To the south you need to see Punta Venado. It is the southern most of the reefs frequented by the PDC dive shops. Because it the farthest south it also does not see as much traffic and is therefore the most preserved reef. You need to dive Sabalos to see the Tarpons at this time of year. Last year I saw a sailfish and 4 marlin during my safety stop at Sabalos. To the north is Los Arcos. This is a deep dive, with a strong current on most days, but it is the only PDC dive that resembles the reef at Cozumel. Those are the top three in my opinion but I still enjoy all the usuals..Tortugas, Baraccuda, Cerebros ect... Plan at least one day in the cenotes. With your 100+ dives I would skip Dos Ojos and head to something a little more exotic. Your dive op will be able to advise you best once you get there.