After a week of intensive diving on a liveaboard, are you going to want lots of boat diving or shore diving? Or a few days of resorty stuff, shopping, restaurants with a little diving to ease back into civilization? Almost nothing on Grand Cayman will be as convienient as a liveaboard. Sunset House is probably the most convienient overall with shore diving on site and boats that leave from there, but I think the quality is lacking. Depends how fussy you are. I've stayed there twice and don't expect I will again as the rooms and grounds weren't that great and I was mostly unimpressed with Sunset Divers. I suppose they're renovated post Ivan and I haven't gone in there since, but I'm pretty sure someplace like Cobalt Coast is still much nicer. I found Sunset House's regular boats to be slow and uncomfortable, and they often dive the busiest part of the west wall with lots of other ops. (It's better when they do the South side.) The shore diving at Sunset House seems pretty well worn. So assuming the Nekton goes to the good stuff as it should, you might be disappointed with the diving at Sunset House.
Cobalt Coast/Divetech is a good option, you can shore dive at the hotel although it's a swim out, or go to their shore dive facility at Turtle Reef a couple miles down the road for some greeat shore diving, or hop on the van to their boats. Divetech is a good op and they dive mostly the North Wall which is better than most of the west wall. You might also consider The Reef Resort or Compass Point and dive with Ocean Frontiers on the East end if you want to head out there for a few days. The Reef is a nicer full resort a couple miles up the road, but the OF main shop and boats are at Compass Point so that's more convienient.
I wouldn't normally stay on 7 Mile Beach for a primarily diving trip, but for a few post liveaboard days I might consider staying someplace like the Westin to do the tourist and beach thing, book a few boat trips with a good op (anyone in that area will pick you up,) and maybe drive to the Divetech shop at Turtle Reef for a few nice shore diving afternoons.