or Compass Point condos on the East End (Ocean Frontiers is there) - much nicer place and better diving than Sunset House. Morritts Tortuga Club (timeshare) on the East End also has a dive op on site but I would stick with Ocean Frontiers.
Cobalt Coast has DiveTech on site but their boats only occasionally leave from the dock there (more likely in summer) and you can't count on that. (It's still pretty convienient though, they pull up a truck right next to the dive lockers and rinse tanks and you toss your gear in, then hop on the van.) DiveTech also has new condos opening down the road this fall that you may be able to rent, but I don't know if they have any plans to have boats leave from there eventually, or even can.
and that's about it. There used to be a few other options that are long gone. I think Red Sail used to leave directly from a dock on property at the Hyatt or whatever it is now, but I don't know if that is still the case and I wouldn't dive with them anyway. I believe there is at least one op that will pick you up on the beach at some hotels on 7 Mile Beach, but I think they would be taking you to the busy and heavily dove sites right off there which is again not most desirable.
Travel to the boat is a fact of life on Grand Cayman. Most of the tourism on Grand Cayman is actually not divers and the locations of most of the resorts (along Seven Mile beach) aren't well suited to docks or shore diving. Aside from the East End, alot of the best diving is along the North wall, which simply isn't close to anything. Time and fuel-wise, it just makes more sense to take a short ride to a dock on the other side and have the boat leave from there, than to run the boats halfway around the island.