I have been over highway 1 many times. What I would recommend is taking 1 up to San Francisco, then 101 to 128 just north of Santa Rosa then back to 1. 1 from Marin to Fort Brag would be terrible in a RV, but it is great on a motorcycle. I have a few favorites on highway 1, Fort Bragg, The Lost Coast, however the lost coast road is narrow and windy, Orick and Crescent City and tour the redwoods. Hiway 1 actually ends at Leggett, if you decide to take the lost coast it will bring you back to 101 just North of Fortuna. You will be on 101 for the remainder of your trip. I have ridden that road so many times all the way up to Astoria and it beautiful, however I did it on a motorcycle not a RV. Best time of the year for the coast is October, summers are cold and foggy. Also if you look at a map, you will see highway 20 runs from 101 over to just south of Fort Bragg, don't take that road in a RV, I have ridden it on a bike and it wasn't fun.
I know the coast very well from Santa Barbra to Astoria Oregon and there are so many beautiful places to see, my favorite is the Redwoods.
