I also chose Caicos Adventures and was happy with them--nice crew, organized boat, good sites, the company of experienced divers (at least when I went). Sandwiches, water and lemonade provided. We dove more or less as a group (I was also a solo diver), turning around based on when the heavier breathers hit their half mark. We were welcome to hang around beneath the boat longer (easy to see with the fantastic viz), but dives ended up being in the neighborhood of an hour. If I have anything resembling a complaint, it's that I would have liked a little more time down there. But I enjoyed diving with them very much. And they had Nitrox; Club Med did not.
We talked to people who went with Dive Provo, and their experiences seemed similar, and they were happy with them. I was at Club Med (not an option for you with kids) and decided to use their dive operation for the first day. They told me that the diving would "not necessarily be better" with another operator, and that diving elsewhere would suck up most of the day. This is because they, like a lot of resort ops, mostly dove Grace Bay. Granted, I only experienced two Grace Bay reefs, but I found them much inferior to the West Caicos spots I visited with Caicos Adventures. Both Dive Provo and Caicos Adventures have vans or buses they send to the resorts to pick up guests. I assume the other desirable ops do as well. It's not a long drive to their docks, and I was usually back at the resort at around 3 pm. And if you pick the right resort, your family probably won't have even missed you much.
As something to do, we rented bikes one day. Not sure if that's a great idea with young children. We met someone who hired a cab for a couple of hours--I think it sort of turned into a "houses of the rich and famous" type tour. I would have liked to have gotten to know the island better, though the bike ride to Turtle Bay helped a bit.
