Waterfalls, helicopters, and gardens: that is what Kauai is good at.
Wailua Falls is a favorite with tourists and artists. Often you will find an easel set up near the falls’ overlook and an artist selling completed works out of his trunk or pick-up bed. The road to the falls (Highway 583) deteriorates as you reach the end, but the view is worth the trip. Opaekaa Falls is on a good road, but it is easy to zip by the parking lot. You may have to turn around in a residential area and return. In Hanalei, ignore the shops and look to the south side of the road at the cliffs. We counted 14 waterfalls one day, and a local told us he has seen 21.
Helicopters are overhead during most of the daylight hours. Their popularity created a growth surge that also led to some fatal accidents. Now more safety measures are in place.
Gardens tours are available both privately owned and nationally controlled. In addition, stuff grows everywhere! A stop at Borders to pick up flower, plant, and tree guidebooks is well worth the expense. And observe the birds. Jungle fowl are everywhere. Before Iniki, they primarily were located in the high region around Kokee State Park, but the storm relocated them. The locals don’t consider them a pest, as the locals in Key West do; they just don’t encourage feeding them.