We loved our ride on Island Helicopters. We took the early morning ride at 8:00 am. Left from the airport, cruised over the south shore, through Waimea Canyon, and ducked in and out of the Na Pali coast before cruising over to Mt. Waialeale, an extinct volcano, which we circled inside of before heading back to the airport.
Helicopter is the only way to really see most of the island, particularly Waimea and Na Pali. We also took a sunset cruise of Na Pali, but the ocean was so incredibly rough we didn't see as much as we would have liked, and I got seasick. The helicopter, believe it or not, was MUCH smoother and more comfortable a ride (though if you do get motion sickness I recommend taking a dramamine an hour prior to the flight).
My skeptical family was impressed and delighted with the helicopter ride. Don't miss it!