You'll receive a list of activities at check-in that will appeal to each and every member of yor party.
Yes, it will be hot. Unbearable may be a matter of opinion since I like that kind of heat while sitting round the beach, but others sure don't.
Personally, sitting by the pool and lounging at the beach are top-notch at HHI.
Otherwise a good dolphin cruise (try Low-Country Adventures), the trip with the Disney Naturalist, pool games at the beach house, fireworks, the campfire and night swim in the Big Dipper and kayaking in the bay are our favorites. We skip the B-B-Que and have yet to try Chef Gordon.
Kids night out at the movies gives you and DW some free time to eat a good meal (see other posts to this forum on dining recommendations) or hitting the outlets.
Best of all is the relaxing nature and easy pace of HHI. You can't go wrong just doing nothing.
Enjoy