I would stay at the Maui Ocean Club, it has a nice pool and waterslide for the kids. It also has a shopping mall a short walk down the beach. You should be able to see the whales that time of the year. Ko Olina (Oahu) is nice with a water slide and really nice lagoons but its a little far out so I think the kids would like Maui Ocean Club better. Kauai Beach Club has a really large pool but is more greared for adults. Waiohai (Kauai) is on Poipu beach and is great for BBQ but the pool is smaller. These are all timeshares and with the kids I think they are a better way to go then the hotels.