It's no secret. If you love the beach, there are tremendous beach communities in Hawaii. Each has its own feel. We were lucky to call Kailua "home" for a number of years. There's a great mix of people there, and lots of small thriving businesses. If you ever find yourself on Oahu, GET OUT OF WAIKIKI and drive over to the Windward side of the island!
Kailua Beach is the largest beach park in the area, lots of families, dogs, swimming, and wind/water sports. Be sure to stop by Kalapawai Market!
If you have access to military bases, Bellows AFB (which is a few more minutes east), also has a large sandy beach with fewer people.
If you like body boarding, Kalama Beach is smaller but has great wave action.
Lanikai Beach is also pretty popular for picnics, although you have to park on residential streets. Just make sure you find public access paths and stay off of private property.
In Kailua, you will want to try Lanikai Juice for a refreshing treat. There are also some great shops with unique, upcycled, hand made jewelry, housewares, and clothes. My favorites are Kailua Verde and Global Village. Lanikai Bath and Body has some really great soaps and lotions. (Beautiful scents, not overpowering... perfect gift for someone on the Mainland who loves Hawaii.)
People who've "known" me for a while will recognize this photo... or maybe just parts of this photo. This photo is the background for my business cards, banner, and many of my online avatars. (It was actually taken in Waimanalo, which is a few minutes down the road from Kailua.) I am not a photoshop guru. This is really the color of the sand, sea, and sky. I love it.