We have done this a few times, from Vancouver BC area.
We have driven the first day to Cannon Beach, Oregon, and then driven the Oregon Coast, through to California, through the Redwood Forests, and stayed over in San Fran. Then drive straight into Anaheim. On the way home we usually leave and go straight to Ashland or Medford to sleep over, and then to Portland to shop a little, and then home. Other times we took the I-5 all the way there, slept over in Eugene, Oregon, one time, and in Stockton, CA another. If I were you I would look on a map of the OR coast, and see what is there that you want to make part of your holiday, and if there isnt anything, then I would just take the I-5. My kids love the Sea Lion Caves and the Sand Dunes, so we have done those on the way.
It is always fun either way!