I have very fond memories of the Marriott Waikoloa on the Big Island. It's not as fancy as the Ritz or JW, but I liked the beach a lot. We went in May 2006 and it wasn't crowded at all. It was going through a renovation at the time, construction was going on but didn't bother us at all. I'm sure it is much nicer now with the new infinity pool. I don't remember that many kids around (like the timeshare properties we stayed at) and rather quiet. We took a stroll one morning along the beach where it stretches out and for my first time saw sea turtles just sunbathing on the beach. That's when we also got to swim with a couple sea turtles. We also saw a hint of the "green sand" which you can only find on the Big Island.
We visited the Hilton next door one day but felt it was way too big of a resort. The Waikoloa was perfect, easy to get in and out, but also nice to spend a day just inside the resort walking around the grounds and the beach.
It was since that Marriott experience (got the room through Priceline) that we fell in love with the Marriott bed (better than the Westin Heavenly bed) and are now loyal Marriott members.