just some add-on comments to the others posts.
You're right about Roatan not being a place for a 6mo old. Besides the airborne Mosquito diseases, the sand flies on the beach are brutal - and bite hard. The hospital downtown is old and tiny.
Really Grand Cayman or Curacao are good options. Cayman is aggressively pursuing Medical tourism so there's a world class hospital there. Also all the boat dive operators pick up at any resort/condo complex along Seven Mile Beach every day freeing a rental car for the others to use. Seven Mile Beach - esp. towards the north end is a wide strip of white sandy beach. There are world class restaurants, waterfront restaurants, shopping attractions like Caymana, the Queens Botanical Gardens, the Buttefly Farm, Turtle Farm etc. You can dive Stingray City with your new diver - it's 15' deep. And non-divers can snorkel at the Sandbar nearby and interact with the rays. Turtle Reef is one of the easiest, shallow shore dives - there's stairs into the water and the mini-wall starts about 20 yds. out and stays around 50-70' max - covered with coral and stuff.
Also you could dive the Kittiwake - a dive cleaned wreck off the west side.
One nice thing is the short boat rides. Some of the dive sites are so close you can see the boats from the SMB resorts on shore. Two good dives and you're back b4 noon. Usually there's 2 afternoon dives also - often to shallower sites as they do their cert/discover dives then. Typical morning dive profiles are 1st deep down the wall, 2nd shallower but some operators offer 2 shallow dives instead. Some of the best is deep but i's all pretty good. Want to get your new diver hooked? Get on a boat to the Aquarium and look for the hovering fish. Those are cleaner stations and the banded cleaner shrimp will also trim your cuticles if you hold your hand still. Then go to Stingray City and feed the rays - it's called the most fun you can have diving in 15'. And dive Turtle Reef to the south - around 40' there's a Tarpon Cave and you can swim with them if you move slow. Plus some of the wall diving is spectacular.
Curacao has St Elizabeth's hospital in town - it's the regional medical center for the Lesser Antilles.
Good boat diving plus many of the beaches are easy entry shore dives with facilities on site including food, showers etc. Some beaches like Porto Mari are family beaches - people stay all day, do a little diving, bbq, hang out in the trees lining the beach. And it's a nice beach.
I'd get something in town or in the Piscadera Bay resort area north of town. The north side of the harbor/downtown is about 2-3 mins. by car from there. If you stay closer - the Dive Bus will pick you up for escorted shore diving - they do the driving, all the work and provide a DM. Usually do two dives at the same location. There's some old forts to tour, the historical brightly painted shops downtown, there's Chrstoffel Park for hiking, the Ostrich Farm, all the activities around the Sea Aquarium (think small Seaworld) and nightlfie if anyone is up for that.
We liked Provo also, Grace Bay Beach is so nice it has it's own website. As mentioned though it's all boat diving and the best is 45-60 minutes away - including the shuttle pickup it can be 90. So it means you'd be gone more of the day - all day if you planned to do 3 dives. And a lot of them are deep wall dives with sharks.
