We love Columbia riverfront RV park in Woodland
http://www.columbiariverfrontrvpark.com/ and Suncrest resort in Moses Lake
http://www.suncrestresort.com/ for private parks, and for Washington state park we like Steamboat Rock. Steamboat Rock SP is close to the Grand Coulee dam and it is fun to go a do the dam tour. We also like Blackwell Island RV park in Coeur d'Alene, ID.