You can spend a month driving the pacific coast of the united states, or do it in 5 days and anything in between. Take this trip. I spend so much of my vacation time abroad, sometimes forget how stunningly beautiful parts of this country are. Plan the trip in the summer or early fall, and rent a convertible if you need to rent a car. Hertz has several convertible options and easy pick-up and drop-off from different airports/locations so you don’t have to backtrack.
The landscape changes dramatically from Seattle to Los Angeles, but each mile has something new and beautiful to offer. If you’re short on time you might consider skipping Washington. I only say this because it could be it’s own road trip. The Olympic Peninsula will blow your mind with the wild and undeveloped coast and the Olympic mountain range. Inland you have the Mountain to Sound drive through the Cascade Mountain Range, and you can drive up the second highest mountain in the United States. Mt Rainier, technically an active volcano can be seen looming over the city of Seattle on a clear day. Definitely plan that trip for mid- late summer many of the mountain passes are closed until the snow has melted and risk of landslide is diminished.
If you do wait to do washingtom on it’s own, Do Portland to LA or visa versa. I reccomend you stop in the floowing places, but this is a trip to do on the fly (except for a few places that tend to get booked in advance – seee below). Just explore, get lost and soak it all in.