carribean in February

My girlfriend and I are planning a trip to the Caribbean in mid-february. I dive (obviously), but she does not. Her criteria are warm, beaches, and sunny. My criteria are warm, beaches, clear water, sunny, and good diving.

We also can't afford to spend too much, so I'm looking for more inexpensive destinations. I don't think either of us want to be run over with super crowded beaches either. Ever see the corona commercial where the guy throws his beeper into the water on a white sand beach? Well...that's basically what I'm looking for.

Can someone suggest possible locations that fit my criteria? I will probably do a couple days of diving...preferably in a place with snorkling also (for her).

Check out the Bay Adventures hotel/air/diving packages to Cozumel. They were about the most inexpensive package I could find when I was shopping in August.