SD to Monterey Via Hwy 1= 1day Big Sur to Monterey is the busy stretch on weekends.
Monterey to Crescent City via 101= 1day, I would stay away of Hwy 1 starting in San Fran because the road is pretty delapidated and narrow, take101 N then west on Hwy 20 (Sweet twisty road) to Hwy1N.
Crescent City to Eugene via coast = 1day
You have to start early in the morning out by 6:30am as soon as daylight breaks to Sundown.
I'm in Monterey area and done these rides several times, for leisured pace you need one extra day, pack light because your bike is already pretty porky.
Enjoy the ride.