Definitely get to Waikiki even if just for a few hours. Lots of people will say it isn't the "real" Hawaii but you need to do it. Try and grab a ride on an outrigger canoe. Awesome.
Maui is terrific. If just for the day, take the helicopter tour or Hana trip.
Big island is all about the volcano. Gotta do it.
Kauai, well I haven't been yet but would love to see the river and pool. Gotta go to Poipu beach.
Pride of America 9-17