Busted, I have stayed at Coconut Harbour 3-4 times. Treasure Island Divers was not the dive ops there at those times, Parrots Landing was when they were open. Coconut Harbour has OK rooms. I prefer the ocean view rooms because they are bigger. They have kitchenettes. Usually breakfast comes with the package. Great pool, good beach diving right off the hotel. They also have diving lockers.
If you want to stay towards the west end check with Fisheye (www.fisheye.com). They usually have packages for hotel/condo/diving. You might also check with Ocean Divers, Cayman Diving Lodge and Cobalt Coast/DiveTech. I have heard good things about all three locations. Have a great trip. Make sure you get out to the North Wall.
RonC.