Agree with Nounou suggestion - a fun little climb.
In the Waimea area, we loved the Awahawahpuii (sp?) hike - down to a stunning overlook of the ocean. However, in Sep 1986, when I was last there, the western hikes toward the ocean had a risk of being socked in - if it looks foggy starting out you may or may not see anything at the end! The clouds broke for us and it was one of the most beautiful sights I have ever seen.
Never got to Na Pali, as my honeymoon trumped hiking!