When in the Seattle area, spend an afternoon and ride up around Mt. Rainier, it's beautiful and the roads are very biker friendly. Some good twisties if you pay to enter the national park.
Mt. St. Helens is another good choice, but I've never ridden my bike there.
Take a ferry and cross over to the Peninsula might be a good option as well. Again, lots of scenery and the ferry can be fun (bikes get head of the line).
Zmilin might chime in with some riding suggestions north of Seattle, he knows those roads very well.

Blue/White 2007 TBA, Thruxton needles, Unifilter, AI removed, Polaris Bellmouth, Bubs, Nology Coils/wires, Lightbar, Ricor Intiminators, Hagon Nitros, Tall Sissy Bar w/luggage rack, Dart flyscreen & Lowers. 130 Mains, TrueGel Battery MG12-BS.