I can't comment on the kiddies question but will comment on the diving. I completed my open water cirtification here (PADI referral). As a new diver I am unable to provide a reference point to other locations but will give you my thoughts for what they're worth.

I completed 12 dives during my stay. The prices are posted on the Sun Diving website, and I believe are a little expensive. You must take a boat for each dive. There are morning trips (2 dives) and afternoon trips (1 dive). My trips ranged from about 8 divers to the most crowded trip having more than 20 divers. I had as few as 5 divers per DM and as many as 8 I believe (not including the cert dives which we were on our own for). I thought the Dive Masters were generally good and my instructor was really good. The majority of the dives are relaxing drift dives. Most of the time there were no other dive boats so from what I hear, its a lot less crowded than some of the Atolls closer to Male. Most of the dive sites were good and one of the dive sites (not a drift dive) was excellent for sharks. I went on this dive twice, and saw roughly 2 dozen sharks the first time (including some baby ones) and about a dozen the second time. Visibility was excellent on all dives and the water is warm (29 degrees celcius). It should be noted that Sun Diving is a seperate company from Hilton, but the dives were charged to our room and we received HH points for the $ spent.

We brought our own Mask/Snorkel/Fins but these are free to borrow from the dive center if you want to do some snorkling and don't want to bring your own equipment.

I don't have my dive log with me, but i can provide more details on specific dive sites and what I saw at each loaction if you're interested.