Aiea Loop Trail
The State of Hawaii's trail resources are awesome, and have every detail you need about this 4.8 mile loop along Oahu's Koolau Range. The trail is easy to moderate mostly due to length, not much of an incline change. It probably could be hiked in less then 2.5 hours, but I meander and take a lot of photos so I always take longer. There isn't one specific overlook, or waterfall that is really the highlight of the trip, but its a nice place to wander in the woods with random stops along the way. I've even read there is a crashed bomber not far from the trail, but I couldn't find it.
Ridge Line Panoramic
Views of H3
Tree Canopy
Rainbow Eucalyptus