I was at the Lihue Costco yesterday and they have some pretty good discounts on 4 activities.
1. $144 for a round of golf, use of cart, and range balls at Makai Golf Course. Good for any time, 7 days a week. You can also purchase this on Costco.com.
2. 20% off Princeville Zipline (you purchase a $100 gift card for $79.99)
3. There was one similar to the zipline for Safari Helicopter
4. 20% Holo Holo Boat tours
Hope this saves some visitors some money.