Hwy 101 takes you through the redwoods and the scenic towns along the coast until you get to where there is to road to Hwy 1 which does hug the coast but includes Mendocino along the way. I would take Hwy 1 and come out north of San Francisco and then Hwy 101 across the Golden Gate bridge and into the city.
There is so much to see at the state parks along Hwy 101 and along the coast on Hwy 1 that rivals anything you can find almost anywhere in the world. Towns like Trinidad, Eureka, Ferndale, Mendocino, Willits, etc. are very special places and not at all touristy types of places.
I-5 is for the truckers who have to make good time and minimize fuel consumption. I only go on I-5 when there is no alternative and even then for as few miles as possible. It has the scenic attributes of central Texas or along Hwy 75 in Ohio in the wintertime.