Based on your question the obvious answer is Highway 101. Then the only choice you have to make is stay on 101 or cut over 1 in California. If you stay on 101 in California once you get South of Eureka you won't see the Ocean again until you cross the Golden Gate Bridge. Highway 1 intersects 101 at Leggett. You can pick it up there and take 1 all the way down the coast. To be comfortable, traveling with kids, the Highway 1 route combined with what you already said, would be a nice 3 day drive with lots of stops along the way.
Per Google, Seattle to Danville on the 101 is 880 miles. Cutting over to Highway 1 and staying on it all the way into San Francisco is 927 miles. That would make for a nice pleasant 3 day drive with lots of stops along the way to enjoy the view.