The Historic Kahuku Sugar Mill is nearby to the recommended travel accomodations, and has a great selection of food and shops!
Located off the Pali Highway, this short hike is friendly for most activity levels. Throughout the hike, you'll go through a bamboo forest, enter into a vast open green meadow, and traverse through a rocky creek until you find yourself at a beautiful waterfall.
Keep in mind this hike is a bit of a drive away from the venue and the recommended lodging.
Not much more to say on this one, head down to the beach when you get a chance. Some recommendations are Sunset Beach, Lanikai Beach, and Waimea Bay. Lanikai is better for those who don't like waves and want to just relax, but is the longest drive from the recommended lodging. Parking can be tricky at any of these locations, so parking a decent bit away and making a trek in may be necessary.