Sometimes it helps to 'just pick one' popular option at each of 2 potential destinations and combine scuba trip reports (here, and if you're a paid subscriber Undercurrent.org) and (for topside, hotel, etc...) TripAdvisor.com reviews to get a sense of how they stack up. I'll propose some...
1.) Bonaire - Buddy Dive Resort. It's a 'resort' in the scuba diver's sense, not a '5 Star luxury hotel,' or large-scale all-inclusive resort sort of thing. But decent-sized accommodations, an air conditioning unit in the bedroom, transfers to & from the airport, rent your (manual, unless you pay more & arrange well in advance) pickup truck onsite, not in town but not real far, nice shore dive with easy entry/exit via 2 piers/ladders, that was my experience a few years back. Not a sandy beach place; for limited sandy beach that doesn't extend into the water, Eden Beach Resort. Harbor Village is the upscale place said to have sand; I wouldn't know. Diver Vince used to post on there and offered rental of
Vinibu, Bellevue #9 & that shows sandy beach.
Bonaire trips tend to kill you on airfare, housing & (shore) diving pretty cheap, food rather expensive, that tank of gas to refill the truck late week will get you.
2.) Grand Cayman - Either Sunshine Suites or Comfort Suites are the 2 'budget' but well-regarded Seven Mile Beach locale hotels I keep reading about, & you get a # of dive op. options. Airfare to G.C. tend to be quite good, people tell me car rentals surprisingly reasonable, but other things tend to be expensive. The most compelling budget option away from Seven Mile Beach I've seen repeatedly recommended was
Turtle Nest Inn.
3.) Little Cayman - Little Cayman Beach Resort.
4.) Cayman Brac - Brac Beach Resort.
Pull up Orbitz or similar & get a package deal price for airfare & resort stay, see if diving's extra & what that'll run, and see how long flights to/from are (you're coming from Minnesota? Travel hassles alone might decide this issue).
Richard.