Have traveled all of US 101 multiple times, and worked along a good portion of it. Like it all, the southern portion is my personal choice.
Ten days for the whole coast is a minimum, but you can get an idea of places you may want to return to later.
My one recommendation: if you like seafood, try a meal at Mo's, there are several along the northern to central coast. Casual atmosphere, good food and service, fair prices.
Crescent City, CA to Portland, OR is about 400 miles, the 90 or so from the coast to I-5 isn't a fast road, try9ing it in one day might be a push.
A word of caution. There are few east-west routes from the coast inland. About the middle of the state is OR38 from Reedsport, father south is OR42 from Coos Bay (with a cnnection from Bandon) and a lot farther south is US199 from Crescent City CA. Hwy 42 is closed or restricted indefinately by a major slide, if for some reason you need to cut your trip short check on the conditions.
It should be an interesting experience for you, hopefully you will like the life style and become one of us, Enjoy.
