San Francisco to Seattle in December

We'd love to give you "great advice on route and itinerary", but 'great' is in the eye of the beholder, and we don't know how much time you have or what your interests are or what your preferred travel style is, so we can't do much tailored to your needs. I can direct you to a few sites here that will give you a taste of just some of the places and roads that a drive from San Francisco to Seattle (and back?) could get you to. For example you could head up either the northern California coast, or head inland up the Central Valley and save your coastal drive for the central or northern Oregon coast.

AZBuck