You definitely want to get out of town... Best to rent a car, a place called Sandy Beach has a beautiful stretch of shoreline, further on down the highway is Makapuu, then I'd just continue on along, stopping where you find what you want. Eventually you end up back in Honolulu. I'd give it a full day if you can as traffic can be problematic depending on where you are, the time of day, and how big the surf is, especially along the North Shore.