Have a look at SIR's brevet routes, especially 600k and longer. They are never easy, but they are sweet.
http://www.seattlerando.org/index.ph...d=56&Itemid=39

Mountain riding in the Cascades is just marvelous. Don't miss what's called Old Blewitt Pass, FS Rd. 7320, paralleling SR 97 between SR 2 and I-90. Near Naches, Hwys 410, 123, and 12 make a magnificent loop. Locals argue about clockwise vs. counterclockwise.