Warning to visitors to Roatan: Them streets are not made of paver blocks and there are no other ski hills than what you see at the "port" of Mahogany Bay
Roatan only looks like that if you go with a Carnival Corporation ship.
For us, we very much use the cruises to decide which islands to visit later, though we haven't yet gone for a land vacation (we keep pricing them out and they cost way too much...)
We LOVED Antigua and want so badly to go back. We enjoyed snorkeling Cozumel so much we decided to get OW certified so we can go back and dive there. This year we are going to Roatan, and plan to go to West Bay to snorkel (or maybe dive if we decide we are really hooked).
We do all our own day trip planning, we don't use cruise excursions except in rare instances (in San Juan we kayaked a biolumiscent bay, and owing to it being so far away from the ship, and not getting back until well after midnight, and just minutes before the ship would leave we took the safe route.)
Cruises are fabulous ways to enjoy many places. Besides a lot of people who 'go to the Carribean" go to an all inclusive and never step foot outside of the resort. They haven't experienced a place any more than the cruisers who don't leave Mahagony Bay. It's all in the kind of vacation you enjoy.
For the record, we've done 3 cruises with Carnival and always felt like safety was paramount to the crew. We decided to branch out and try something new, not because we've lost faith in the company but because 3 similar vacations (the onboard experience is 'consistent'- meaning, pretty much the same thing) we want something new.