If you are looking for an alternative to Waikiki Beach, look no further than Ko'Olina Lagoons. Located in the Ko'Olina Resort Area, these four man-made lagoons are perfect for swimming at any time of the year. Each lagoon has a different name: Kolola, Hanu, Nai'a, and Ulua. You will need to rent a car or catch The Bus to get there, but the 20 mile drive west of Waikiki is worth the trip. Every time I have been there, the lagoons have been almost isolated; very different to the crazy hustle and bustle always present at Waikiki Beach. The lagoons make a great place for a picnic, perfect for families, with grass areas surrounding the lagoons and plenty of shade to relax. Two things to be careful of: slippery rocks that separate the four lagoons, and the current - it can be strong enough to suck you out to sea depending on the weather conditions.
If you prefer to avoid Waikiki completely, and you have a Timeshare, you can stay at the Mariott Ko'Olina Beach Club, which is in walking distance of the lagoons.