Oh man, I did a similar trip with my brother last summer down from Vancouver, looped back via Las Vegas, Death Valley, Yosemite and he i5. Such a blast.
How much time do you have? Some suggestions: Day 1: Seattle to Portland to Cannon Beach Day 2: Cannon Beach to Florence Day 3: Explore the Dunes around florence (must) Day 4: Florence to Redwoods. You'll pass a big sign that say 'Zoo Safari' or something. Stop Here. Really reasonable entry price and we were impressed with the range of animals. Chimpanzees. Kangaroos. Tigers. Awesome petting zoo area. Day 5: Explore the redwoods (you could spend a couple days exploring really). Day 6:Redwoods to San Francisco Day 7: Explore San Francisco (or longer) Day 8: San Francisco to Big Sur/Monterey/Carmel by the Sea Day 9: Monterey to Malibu and Venice Beach
Just take your time. Stop lots and don't spend too much of any day driving or you'll pass everything. You will find lots of places to stop. The whole 101 is beautiful. I'm excited for you.