I don't claim to be any expert, but I'll get this thread rolling. As far as I could tell, the Caymans doesn't really do the true "all-inclusives", like Jamaica, for example, with resorts like Couples and Sandals including absolutely everything, including diving. Grand Cayman does have some dive resorts though. (can't speak for other 2 islands) I haven't stayed at them, but we dined and/or dove at a few, and I was taking note for possible future dive shop trips.
Sunset house has a great location, fairly close to town, but too far to walk. On Grand Cayman you need a car to not be resort bound. They have a restaurant and an outdoor bar/restaurant. The resort itself *looks* basic, but hey, I didn't see inside the rooms. They do have shore diving right there.
We also dove out of Compass Point. The dive staff were excellent there, and they are really into pampering (bringing gear to/from boat, rinsing, hanging, setting up gear on board, etc.) The resort itself looks really nice, even have a bit of a beach, which Sunset doesn't have, but I don't believe they have a restaurant (I even checked their website) Also, they are quite a ways out in the East End.
We also checked out Cobalt coast in West Bay. It's close to the North end of SMB, so better location. We didn't dive there, and in fact the shore diving was a no-go due to weather. The Divetech staff seemed friendly and helpful though, and they get good reviews. The resort looks pretty nice and they do have a restaurant.
Oh, and we had lunch at the Macabuca? tiki bar (Cracked Conch). They have shore diving there, but no resort.
That's what I found out in just 3.5 weeks there. I'd love to hear more feedback on these 3 and others that I may have missed?
Shore diving is not like Bonaire where you take your tanks in your truck and stop anywhere and dive on easy access, well marked sites. Each resort requires you to rent tanks from them only (even post big "no outside tanks" signs).
Weird thing (and I just have to say it) is that if you aren't staying at one of these places, night diving is a pain in the butt. They typically close at 5:00 (or a bit earlier if they so decide to close up early), so you have to get there well before, then hang around until at least 6:30 to do a night dive. Hence we had many dinners at Sunset house waiting for dark (perhaps that's their plan) after the guys rushed from work to make it there on time to get tanks. One day we didn't make it (because they closed early) and went to Eden Rock (open until 5:30... maybe), but then couldn't take the tanks to Sunset house. And then when you get out they're closed, so you have to take the tanks home and back again next morning. It's a strange system, but I guess no staff want to bother hanging around for night divers. I personally far preferred boat diving.