I'm not trying to argue with you but that package is pretty limiting for all the money - it must be $50 r/t for a cab to take them to Georgetown from CC should they tire of the food or nothing else to do. And a pretty marginal beach.
Or rent a car that sits most mornings for about $400/wk. to be able to do other shore dives when CC is shut down and the other dives too far south for CC to shuttle them to. How many afternoon boat dives does that package include?
I could see it if the budget was $3K - including air.
I'm not arguing with you either, just stating the facts, that package includes 5 afternoon dives, including the Kittiwake and Sting Ray City at no extra charge, see below:
6 x 2-tank AM + 5 X 1-tank PM boat dives (17 boat dives for 7-night package)
Shore diving on resort's house reef off the dock (weather permitting)
Package PM dives may include trips to the Kittiwake and Stingray City at no additional charge, depending on weather
It also includes:
All meals, lodgings, and 3 drinks per night
Airport ground transfers (so there's no $50 rt cab fare needed) and it includes:
Resort fees, taxes and gratuities - except dive gratuities which are NOT included
Nitrox is also extra, but it is a pretty inclusive package, but as I mentioned, the shore diving is unlikely in January because of the winds. The beach is small and manufactured, but they have recently updated the beach and pool area and decking and installed a jetted hot tub and new shore diving facilities.
Did the OP ask for a good beach? I may have missed that. But some of the places he has visited are not good beach destinations - like Bonaire - and some of the suggestions made by others are not good beach options either.
You don't have to rent a car and travel and eat elsewhere on the island if you stay at Cobalt Coast unless you want to, and it doesn't cost $400 to rent a car, at least not in my experience. Car rental is one of the few bargains on GC IMO. A compact car is about $140 for the week, plus the $20 drivers permit. My credit card covers collision and damage in a foreign country, but third party liability is extra and so is road side assistance - if you want that option; but if you have been paying $400 to rent a basic car on GC then you have probably been paying too much.
Grand Cayman is not what I would pick for a January dive vacation because I like warmer water - I wouldn't go to Provo in the T&Cs either, and it is just as expensive as GC, if not more so, and the water is even colder and the reefs are further away.
And we like the chance to enjoy the many amenities available on GC when we visit so we don't stay at an all-inclusive, but a lot of people go to Grand Cayman in the winter, it is peak season and the dive boats are full. And many of the dive ops load passengers up from West Bay Marina and dive the sites on the West and South sides due to the winds, not just Reef Divers.
So if someone is looking for an easy, nearby, and reasonably-priced option, with good diving, then Cobalt Coast is a consideration IMO, but there are other options out there - it's a big world.