HHI is out favorite family vacation starting when our kids were young and now with their kids.
The beach at HHI is usually very kid friendly. Very flat a long way out which causes little tide pools that kids can splash around in. The waves are gentle unless a storm is brewing.
The resort itself has several areas of lawn-type games scattered about. Even the littles can enjoy tossing a ball or pushing a puck. There is an activity/craft room. They can fish or crab off the pier. There is a pool at the resort and one at the beach.
A couple of mini golf courses nearby.
When our grands were too little to ride a bike themselves we put them on a bike with an adult in a sort of shell attached to the bike. Put them right to sleep.
The only eating places at Disney are quick serve walk up window type places, one at the resort and one at the beach. Several restaurants within walking or biking distance that are fine with kids. Grocery store very close.
Weather is changeable... Look online for average for month you are going. But know that all it takes to change that is a warm front or a cold front.