Most scenic places on Kauai are hidden in rugged and inaccessbile terrain. However, one easy place to get to, and not too far from the resorts in Kapaa is the popular Wailua Falls. It is located on HWY 583 (Maalo Road) just south of Kapaa, before Lihue. This waterfall is probably the biggest by volume of water that one sees in Kauai. As luck would have it we were able to see Wailua Falls with a rainbow. It's probably not all that rare, since Hawaii is the rainbow state afterall.
A great place to stay is the Hilton Kauai Beach Resort, located just five minutes north of the Lihue Airport. There is a nice beach, pool and its location allows for shorter day trips to the popular places such as Waimea Canyon on the west end and Ke'e Beach near Princeville. Another benefit to staying on the east side of Kauai is that there are more grocery stores and restaurants located in Kapaa and Lihue than elsewhere on the island.
For a great view overlooking the east end of Kauai, hike up the Nounou Mountain Trail. It offers 360 degree views of the towns of Kapaa and Wailua below. Looking west you see Mount Wai'ale'ale only about five miles away. It is the wettest spot on earth - averaging 440 inches of rain annually. To get to Nounou Mountain Trail, drive about a mile in on Haleilio Road. The road is located just south of Coconut Marketplace in Wailua. Nounou Mountain Trail is much drier so it isn't as difficult of a hike as other Kauai hikes along the Na Pali coast. Looking north from this trail you can see Sleeping Giant in the distance, which is known as the King Kong Mountain.