The better beaches on the Big Island are the ones you have to drive to. Hapuna Beach, or the beach at the Mauna Kea.
We have stayed at the Bay Club and Kohala Suites, all with RCI trades. Never traded into Kingsland, it didn't really appeal to us as we're not big pool people. We like a pool on site, but it doesn't have to be anything fancy. Access to the pools at the Hilton wasn't all that appealing either. We stayed one night at the Hilton, before there were timeshare units there. Our kid got kind of bored of the pools within a few hours, and they were very crowded.
Of the two properties we stayed in we preferred Bay Club as the units were larger. We really liked being on the first floor where our daughters could just walk out to the lawn to play there.