My personal would be I20 to I10 all the way into CA and then take 210/30 which goes across the top of the LA basin missing most of the traffic, especially mid day or on a Sunday. The 210 to the 118 to the 23 to the 101 north, at San Jose I would take either I**) or I680 to loop around San Francisco as the 101 becomes city streets. Follow the interchanges to get you back to 101 at San Rafael and take it all the way to the Columbia River and then into Portland area. This will miss the most hills and traffic and snow or ice. The 101 is gorgeous for most of it's length in both states.
