We had an extended family celebration there for my MIL's 80th birthday. We loved it there. It does not sit right on the beach. They run a shuttle to their private beach house. You can walk to a marina and there are a few restaurants/shops there. We were just there to spend time with family so we didn't plan a lot of activities. We did go on a tour of a distillery and ate at some yummy restaurants. They have planned family activities, bike rentals, shuffleboard, etc. We loved that they brought us samples of Dole Whips while we were playing shuffleboard!
I think it would be a great place to unwind after a trip to the parks. As far as how many days goes...I can't tell you. HHI offers a lot of things to do, but you might also just like chilling out!