depends on what you like to skate but one of the favored parks in the area is known as Tron, its at the Tualatin Valley parks and rec center in Beaverton. Good street and tranny sections and you're bound to run into some friendly locals
As far as street skating goes, I've found the Goose Hollow area surrounding Exit boardshop to be really fun, lots of mellow hills and ledges to find. also don't forget to check out Lincoln high in that area, the famous schoolyard with red and white ledges and a couple large handrails to gawk at