Makapu Lighthouse is a nice paved walk/hike with great views. The North Shore is fun for a day trip to see the famous suef beaches. I'd recommend going through Kaneohe on the way up or back from the NS. It takes twice as long as the H2, but it's one of the most scenic drives in the world. The NS town Haleiwa has lots of restaurants and touristy shops. It's a nice place to walk around and have a meal. The Turtle Bay hotel on the NS has a nice public beach for the kids and the outdoor hotel bar has a killer view. If you can get one of the small number of reserved spots, Hanauma Bay has great snorkeling and a really cool beach. I'm biased because I live in Kailua, but imo the beaches there, including Lanikai, are the nicest on the island. A lot less crowded than Waikiki and you don't have to worry about someone stealing your stuff if you go into the water. Another often overlooked beach that's really beautiful is Malakahaena on the way to the NS. Great body boarding. There are amazing hikes all over the island if you're into that. I'm happy to give recs depending on difficulty level.