One thing I've figuerd out when vacationing with family is that it's much nicer if you can get a vacation rental or suite rather than a typical hotel room. Then you have a living room, the option of eating in (eating out every meal gets old after a while), etc.
Hilton Head might be a good option for you guys. Tons of nature, and very civilized, all right next to each other. You should check out this Marriott:
http://www.marriott.com/hotels/travel/hhhvi-marriotts-grande-ocean (there are others on the island, but that one would be ideal) or stay at Sea Pines (
http://www.seapines.com/). You can rent bikes for the entire time you are there, and practically everything you would want to do will be accessible from the bikes, including eat at great restaurants. There are extensive bike trails throughout the island, and you can even ride your bikes on the beach at low tide. You can rent kayaks or horses or go on a boat tour (I recommend
http://www.dolphintourshiltonhead.com/trips_3.html). There are a couple of Orlando-style mini-golf places (ie, lush, over-the-top mini golf; very fun), but other than that Hilton Head tends to be a subtle sort of place. I don't think it has a lazy river or snorkling, though. For that, I would recommend the Keys (oil spill isn't affecting it yet, but probably will be soon), or going to Mexico or the Carribbean. If you don't want to mess with passports, you can always do Puerto Rico (or Hawaii...) Let me know if you're interested in Puerto Rico; I can make some recommendations.
Hope that helps.
