Aloha Jer, Kaena Point is a good hike, so is Diamond Head. As for beaches, the ones I prefer are North Shore and also Waikiki in front of the Moana. Then of course there are all the beautiful ones
Aloha Jer, Welcome to Hawaii. How nice to have your family come and visit :-) I am not sure if your parents are in good health and want to go on hikes, swim or rather shop and do "easy" stuff.