jenbengen
Watch it
I was stationed in Hawaii for 3 years. Just for your info, milk at most stores in Hawaii are not local, that's why they cost about 5-6 bucks a gallon. Waimea beach and the Dole plantation are good place to visit.
Waimanalo beach in Kailua is nice and not crowded. If you are a veteran, try the Air Force's Bellows Recreation Center in Waimanalo, great beach with cottages, camping/fishing area.
If you want the "Grand Daddy" of tourist activities, go to the Polynesian Cultural Center. They have the complete package, depending on your budget. For a more authentic Luau, go to the smaller ones north of the old Barbers Point Naval Air Station.
Just remember that Waikiki is a tourist area and the prices are higher than the rest of the Island. Oh, don't forget to go to Haunuma beach and mingle with fishes or climb (40 min) the Diamond head for the spectacular view.
Enjoy the visit and be a Kama'aina.
Forgot about the cultural center. That's a great place to go.