Lake Chelan State Park
This is more of a state campground than a state park, but it is great little area outside of the tourist crowded city. There are quite a few spots where you have plenty of privacy from your neighbors, which helps with noise since there can be loud teenagers around. The shower/bathroom facilities are not stellar, but hey its a campground shower. The swimming area is nice, with grassy and shoreside areas to lay out. There are also large playfields with courts which people were always welcoming in others to play. The place is busy, but worth the fight to get a spot during the busy season.