Whatever route you choose, you can reach an eroded hill at the Koolau summit in an hour and a half with little difficulty. Absolutely wonderful views of the Waimanalo coast and of the coastline from Hawaii Kai to Diamond Head are your rewards.
For the brave at heart, a half-mile ridge-walking balancing act to Pu'u O Kona can be attempted. To do this, head left along a crumbly, thin ridgeline once you reach the eroded hill. Satisfied with the view we had and not wanting to risk life and limb, I opted against the Pu'u O Kona ascent. My reward? I'm here to write this for you.
Options for this hike are to hike to Pu'u o Kona and return to descend the switchbacks or continue on along the crest to a distinct hump on the crest about 20 to 30 minutes beyond o Kona. Once at that hump, it is possible to follow a trail makai and follow it until bottoming out at a vacant lot near the end of Papahehi Place in Kuliouou Valley. The descent from the summit hump to Papahehi Place takes about 1.5 hours and includes a narrow dike section and two steep slopes where cables are affixed. We call this route, Kuliouou middle ridge.