If you're interested in back-of-the-beyond type diving (and not the Coco View/Fantasy Island preference) I'd recommend Corn Island in Nicaragua. Well worth a week. Another b-o-t-b place is Cayos Cochinos in the Bay Islands. Both these places require a teeny bit more work to get to, but once you're there, it's perfect.
My personal view of Roatan is that it's badly overdeveloped. The boats from AKR were coming to Cayos Cochinos to dive, but I hear there are still fine places to dive Roatan. Utila is heavily developed as well, but smaller, easier to get around, less tony (except for a couple places) and a heck of a lot cheaper than the $150 per day per person or more at some of the top end resorts.
=Terry