Emily:
Here is the approach we take while zipping along the Western Front.
North I-5 in an air conditioned car past LA and through the valley as fast as possible with as few fill-ups as possible. Then the fun: basking in all the cool water stops from Yosemite; to Ashland, OR; to hwy 101 up the coast; beach combing (newf says: come on mom let me go in the water, then, come on mom I'm wet let me sleep on your sleeping bag); coffee on the beach; newf naps; slow progress north enjoy the state parks; in-land to Portland for a Truman visit; back on I-5 and a quick 3hr zip up to Seattle.
But really, we try to eat at a lot of street cafes so the dog can curl up under us; lots of water. Don't rush, take a scenic route, better sidewalk cafes than on the interstates.
And, best of all, in Oregon, especially on the coast...all the kids can identify the dog...they all know Lewis & Clark had a Newfie named Seaman. (There's even a statue at Seaside.)Dawdle...and enjoy a little vacation with The CLEO.