Much as I love Guatemala, check it off the list as a scuba destination. Belize (an atoll or maybe Caye Caulker or Ambergris Caye) and Honduras (Bay Islands) are great choices, though. My photos, blogs, and travelogues are below. Happy trails!
http://www.flickr.com/photos/staceyholeman/collections

Great photos and blogs. We'll look at Belize options. Thank you very much.

March is a breezy month and great for sailing and windsurfing. Belize has the largest barrier reef in the hemisphere, at 190 miles in length, 3 of 4 atolls in our hemisphere and another 220 miles or so of patch reef coral.

Another vote for Belize. We saw nurse sharks, lots of tropical fish, eels, lobster, rays, and sea turtles there. Some of the best snorkeling we've ever done. If you want to, you can do a split between a jungle lodge to see wildlife and then head to another location for your beach time.

I love Costa Rica but wouldn't recommend it as a snorkeling/diving destination. Amazing wildlife though.

Belize or Roatan would work nicely

Love the idea of Belize, and it does sound like it would work to split our time between a jungle lodge and the beach.

Any particular recommendations about best places to stay near snorkeling-scuba-windsurfing options on the beach, & most interesting jungle lodges?

I love Costa Rica, too, but Belize seems to make more sense, & sounds wonderful.

Thanks, too, for any suggestions re Belize lodging, restaurants, etc.

Very much appreciate your help!!

We did a split between the Cayo District and Ambergris, stayed at Chaa Creek and Victoria House - both excellent. Ambergris has a lot of good restaurants; at the jungle lodge, we ate all our meals there since they tend to be isolated. These are kind of pricey places, but there's a wide range of accommodations.