In the summer you can have a picnic underneath the Ironwood trees and in the winter you can catch a good wave at Kalihiwai Beach in north Kauai. The swimming is usually good here. Even the kids should be safe, just monitor conditions carefully. Waves tend to be harsher during the winter, there are also a few slippery rocks and some coral you should watch out for.
To reach take Highway 56 west from Kilauea toward Princeville. Turn right on Kalihiwai Road just before mile marker 24. Parking is located near the end of the road. There is no lifeguard and no facilities.