this question is much more difficult to answer than the helicopter one.
We have done the Luau in Maui, because it was offered from the travel agency close to our hotel.
It was a nice evening. Food wasn´t that good, but the dancers and singers on stage were nice.
But it`s not worth for us to see it a second time.
When you´re in Honululu or Waikiki spend some time walking around in the evening in Waikiki, have fun in a nice beach bar, go to the market in the center of Waikiki, try some food from different asian cuisines (less expensive than eating in a restaurant) and enjoy.
During the day make a tour over the island or when you like shopping take the public bus to Honolulu, there is a big shopping mall (sorry, forgot the name, its 6 years ago).