Entiat City Park
This was a great place to take the kids for a weekend to swim at the lake. There is a picnic table at each spot it seems, which is convenient. There is pretty much zero privacy though, so expect to get acquainted with your neighbors. The area is clean and the beach is nice, not very wide, but does run the length of the camping area and has a nice little dock to swim from, just be careful of oncoming boats, especially if it's your little ones playing out there!