East Side -  Wailua River State Park (Hike to Secret Falls also known an Uluwehi Falls, Can kayak in the river if interested), Drive by the Wailua Falls as well (this is the 80 ft double waterfall). 

North Side - The Na Pali Coast (Can't access by car, will have to take a Cruise or Helicopter - better at sunset time), Snorkeling at Tunnels Beach, Hike the 1st 2 miles of the Kalalau Trail to reach Hanakapiai Beach, Explore Hanalei Bay & Town, Kee Beach. 

West Side - Drive all the way till Kalalau Lookout in Waimea Canyon State Park and explore Hanapepe Town (has a swinging bridge & some shops)

South Side - Poipu Beach, Spouting Horn, Mahaulepu Heritage Trail