Have you been to the park at Hudson's Bay in Vancouver. It's a Multi-Million dollar facility that was ranked #1 by the Seattle Times a couple years ago. The money was donated by a very wealthy, generous, baseball loving alumni from what I've heard.
If you're looking for complete wow factor, something that will make you feel like a ballplayer from that era of the 20's and 30's, then you need to make a trip to Hoquiam's Olympic Stadium. Without a doubt in the state of washington, this is my favorite place. You can't know how amazing a spectacle it is until you've played a game there on a warm summer's night.
In Eastern Washington, Selah's ballpark has the feel of a minor league stadium with a terrific set up. It's a wonderful place to see and play a game. Ephrata has one of the better kept actual playing fields in the state. They have a beautiful park as well. Also, for that small town baseball lover, check out the park in Colfax. Set against a mountainside, it inspires any baseball lover.