I too have just completed a trip... My father, brother and I visited Mt. Saint Helens, Crater Lake and returned via the Pacific Coast Highway. Awesome trip with all goals completed... twisties and as little I-5 as possible.
If you get a chance, visit Mt. Saint Helens, such a sight and the roads are sooo much fun. NF-25 too many corners to count. NF-99 is super-scenic, just not quite as fun to ride with all the rocks on the road and lack of run off (more like drop offs).
SR-821 from Ellensburg to Yakima. Do not do the 82/97 if you can help it! Take the Old highway, a winding canyon backroad following the river. It was high 90s...
Go to Crater Lake! 7200' up, did some of the rim drive. Took the SR-138 to Roseburg, 43MPG (on my VTR!) as what goes up must come down. Gentle twisties. followed by the SR-42. Lush forest.
Then north on the Pacific Coast 101 to Florence, and some ATV'n in the sand dunes. Back on the 101, over the huge bridge at Astoria reaching across the mouth of the Columbia River, Port Townsend, caught a ferry to Whidbey Island and back home to Vancouver.
About Six days, around 3000km.
Pics here: http://www3.telus.net/vfr/gallery/cr...e04/index.html