You pretty much just described:
Curacao
Grand Cayman
Bonaire (maybe)
Maui
Just about every shoredive (15-20) we did on Curacao was on some sort of beach, except for a couple of the better West End sites that are on ironshore. But there's also some really nice beaches, Sunset Waters Resort has one, Porto Marie is one and they dot the coast line both north and south. Some of them are pretty dramatic as they're surrounded by ironshore cliffs that are 40-50' higher. If you want to stay right on the beach though, that would be Sunset Waters or one of the closer in-town resorts like the Marriott, Hilton or Lions Dive to the east. The Marriott is really nice if you're looking for something upscale, great pool complex and it's own beach/cove. They also have an onsite diveop - most resorts on Curacao do. Curacao can be a little trashy in some areas though, mostly downtown and around the refinery. We were warned to lock our vehicles and hide anything we left. There's two daily flights from Miami that are real convenient - I left Houston at 6am and was there by 2pm.
Grand Cayman has Seven Mile Beach it's all really nice beach but there's no shorediving along it - except at Cemetary Beach. But good shorediving 10 mins. away in either direction. Not as many named sites as on Curacao but there are dozens if you contact one of the locals for details. I could come up with over 1/2 dozen excellent named sites without much thought but most are off ironshore - they have ladders etc. for easy entry everywhere. Stingray City is also a riot. And being the offshore banking capital, I don't think there's a lot of crime...lol.
You'd have to work a little harder to find a nice beach on Bonaire, but it's the shorediving capital of the Caribbean with about 60 named shoredive sites. Most of the resorts sit on ironshore though so to stay on the beach look at Plaza Resort, Harbour Village or Eden Beach. The Divi Flamingo also has a small beach. One problem with Eden Beach is that if there's a cruise ship in town, their beach could be crowded. There are a couple of public beaches like Pink Beach which is also a pretty good dive, but none of the beach areas on Bonaire have any sort of facilities nearby - except Lac Bay where they windsurf.
Maui has great beaches, plus more than enough shorediving for a week or so. Some of it would be a small drive depending on where you stay though. And lots of other non-dive activities. From what I've heard/read (family member was just there) Hawaii is really suffering from a lack of tourists due to the economy and airfare prices. That's where I'd go, an uncrowded Maui would be deluxe.
ShoreDiving.com - Your Shore Diving and Snorkeling Web Community! lists options for all these areas.