A couple of disclaimers: I prefer secondary roads to freeways. I like to set the cruise control at 50 mph and look around. I also dislike crowds, so I do most of my travel in the late fall or winter. I also prefer the more remote locations. I get a $10 road atlas and look for roads with the dotted lines indicating a scenic route.
That said, I would recommend starting exploring the West Coast at Highway 1 north of San Francisco. (I spent almost a year at Fort Ord and was not impressed by ice plants and zillion dollar homes)
If you are not bothered by heights, I would recommend a walk across the Golden Gate Bridge. I would suggest the east side, so you can see into San Francisco. After that, I would watch for the exit to highway one about Mill Valley, I believe. At Inverness, there is a junction to Point Reyes. That might be worth a day. You can explore a lighthouse and/or walk a heck of a long way north along a sandy beach (very dangerous rip tide so avoid the water). At Bodega Bay, you may see large wading bidrs feeding in the bay.
Take 1 all the way where it joins 101 at Leggett. (I love the rolling grassy hills)
At South Fork I suggest you check out the Humboldt Redwoods State Park. The road west winds through humongous redwoods that make the Douglas Firs of the NW look like pulpwood.
That road eventually leads to Petrolia and Cape Mendocino back to Ferndale. It is rarely traveled and the beach is deserted at the coast. But you probably won’t want to take that side trip.
Unlike the northern California coast, The Oregon Coast is much more rugged, heavily forested and colder and wetter.
If you want to bypass Portland, you can take 30 East to Kelso-Longview or cross the Columbia at Astoria and take 401 to 4, either way, not much to see. Downtown Portland along the river has been spiffed up considerably and may be worth a stop.
Regarding Washington, Heading North on I5, you might want to stop at our sawed off Mt. St Helens just so you can say you saw the local volcano. You do want to get to Ft Lewis by about 3 PM. By 4PM the freeway plugs up from South Tacoma through Seattle. It clears out between 6 and 7, so you might want to get something to eat instead of waiting in the mess.
In Seattle, I would recommend a ferry boat ride (as a passenger, no car) timed to catch the setting sun highlighting the building of downtown Seattle. Afterward, you can check out the music in Pioneer Square. You may want to take a day trip to Mt Rainier, but then again you can see it on any clear day. As far as the Olympic National Park, us natives are not impressed by rain forests. We have 50 words for rain, all preceded by an obscenity.
As far as wild life, the best time to see something is at dawn or dusk. Also, gas is highest in Washington, due to state taxes, and in Oregon, you must let the attendant pump the gas.
Have fun