Grand Cayman is very expensive. All food definitely is since it's all imported. And you've chosen the end of high-season so rates will still be elevated till about April 15th/May 1st.
A third quieter option is the Reef Resort - an AI on the much quieter East End. There's only 3-4 resorts/condo complexes out there, 3 dive operators - including one at the Reef and 7 restaurants + 1 food store. And a 45min. drive for everything else back in Georgetown - which is a busy cruise port. It's not unheard of for 4-5 ships to be in port the same day in winter months. Also Seven Mile Beach which is the west side of the island is also very touristy/busy. Cobalt Coast - the north side AI - is far enough for that not to be a factor. Sunset House - the other semi-AI (dives, room, breakfast in their package) is a little south of Georgetown so relatively quiet. At night after the cruisers leave, you can walk to very good restaurants in south Georgetown pretty easily.
Diving off Cayman is excellent. The North Wall (Cobalt Coast) especially.
Dive in Cayman, Grand Cayman Diving, Cayman Islands Scuba Diving show more in videos than I can describe. IMO the best shore dive on Cayman is Turtle Reef - under a mile from Cobalt Coast to the west. Sundivers is on-site there for tanks - it's co-located with the Cracked Conch restaurant.
Cracked Conch Grand Cayman Ocean Front Seafood Restaurant and Tiki Bar
If you're considering Roatan/Cocoview consider Anthony's Key also. It's a little nicer, the amenities are better (small beach, pool on the Key) and they do 3 real boat dives instead of 2/2 drop like Cocoview. The shore dive is better at CCV though since they've got the Albert Wreck just off the resort and the wall. The AKR shore dive is shallow for a long way out.
One advantage to AKR currently is they have a BOGO going on in 2016 across all their amenity levels.
2 for 1 Travel Deal | Anthony's Key Resort | Roatan | Honduras - I'd pop for a Superior class room since that means Air-Conditioned. Even in late Feb/Mar it could be a little steamy - we were there the end of March and some days it was very hot/humid - the AC is nice since it dries the air. One thing to price on Roatan also is the flights - this close to your travel time you likely won't find much under $700 or so. For more on AKR the ScubaBoard trip was there last year -
http://www.scubaboard.com/forums/scubaboard-invasion-2014-a/
Both resorts are pretty isolated so generally quiet at night. I've been to AKR once at night when it seemed like the only person we ran into twice was the night watchman. Although the restaurant was open, it's up the hill on the mainland side not the Key. One small advantage to AKR is it's a five minute cab ride to the West End if you tire of the AI food or want to do a little shopping etc. Some people spend all week at CCV and never see any of Roatan except thru the shuttle windows. Wouldn't be for me personally, I like to experience the people/places where I dive.