Facing a distantly similar situation, I've been looking into a Florida Keys trip. You can stay at a hotel on the marina, close to your dive boat, go out for 1 or 2 2-tank dives per day, yet rent a car for the week and let the rest of the family drive off and do whatever at Miami or the Everglades, etc... (Key Largo is where I'm talking about going, and they're got a couple of dolphin encounter places there, which could thrill a 6 year old - and many adults, too).
You could do much the same thing staying at West Palm Beach in a hotel, though you might have to drive to the dive shop in the morning, and do a 2-tank boat trip with one of the shops (e.g.: Jupiter Dive Center - which can rent 120 cf steel tanks, and nitrox is an option) for drift diving, seeing bigger animals like goliath grouper and maybe sharks, etc...
My point is that you don't have to choose between staying at a Sandals type resort or a live-aboard, or a 'dive-centric' location like Cocoview in Roatan, or even leave the United States, to get a dive vacation that lets you dive a lot but also entertains others.
Richard.