I am flying in to Portland and driving up to Seattle. I have 4 days - what are must sees.

What kinds of things are you asking about? Portland to Seattle is a simple drive on a freeway (I-5) directly south to north and takes about 3 hours.

to "see" anything of interest you'll need to make a detour one direction or another. A few possibilities include: Columbia River Gorge? Willamette Valley? Oregon Coast? Washington Coast? Mt. St. Helens? Mt. Rainier? Olympic National Park?

I was thinking about doing the following... Columbia River Gorge then over to the Oregon Coast - would like to see a sunset on the coast. Either drive up the coast and go to Olympic National Park - or head over to Mt Rainier.

Sure, all good ideas but you'll have choose with only 4 days. Personally I would pick the Gorge and OR coast, then just drive straight up to Seattle.

For Washington, Mt Rainier probably works better for a short stop that ONP (which is HUGE and spread out and you could easily spend all 4 days there and not see it all and have quite a bit of boring driving).

To see all four places you mentioned, I'd estimate more like a week or two to do them justice.

If you are flying in and out of PDX, it is possible to take the red line light rail into Portland and see several things and then take an Amtrak Cascades train to Seattle. The Seattle King Street Amtrak station is close to the stadium where the Seahawks and several other teams play. If you feel you must have a rental car, you can probably rent one in downtown Portland for less than renting at the airport.

Between the Gorge and the Coast, I personally would 100% pick the coast, no contest.

Day 1: Pick up rental car, leave Portland. Drive to Yachats & Cape Perpetua. (on the way down you could stop at either the the Evergreen Aviation Museum in McMinnville or Silver Falls State Park, whichever interests you more.)
Day 2: Yachats up the coast to Astoria, including Newport & Cannon Beach
Day 3: Astoria & Cape Dissappointment State Park
Day 4: Astoria to Seattle, drop off rental car. (This is only about a 3.5-hour drive, you could probably add a stop along the way if you wanted. Mt St. Helens is doable.)

Yachats is a great suggestion when on the Oregon Coast.

Thanks... will do the coast!! Looks beautiful!

patNels - In May, part of our Oregon trip was along the Oregon Coast (link to trip report below ... Chapters Four through Seven). Our hotel in Yachats, as you will see, is among our all-time favorites. We got the Queen-Queen-Picture Window (Whale Watcher) room. $221. Perfect. Lots of lookout spots on way up, but be careful, most are located on the other side of 101 as you head north. Heceta Head Lighthouse (photo below) is a wonderful spot to stop along the way. Loved Cannon Beach, and I wish we'd spent a little more time in Astoria, as this historic town has some interesting sights. Enjoy your trip. (Evergreen Aviation Museum in McMinnville was also terrific ... took a tour of the Spruce Goose ... worth the extra bucks ... Chapter Three)

https://travelswithmaitaitom.com/oregon-no-cal-2021/

I'm not inclined to join the "coast bandwagon" until I know when this trip will take place. Is it this summer? Next spring? For example, in some places along the coast, especially popular ones like Cannon Beach, you're likely to encounter 2-night stay requirements. Or, in late summer, the heat and risk of smoke from forest fires, of which there are numerous and disastrous ones at that, can impede visibility and one's enjoyment of the mountain areas, including the Columbia Gorge.

On the other hand, by mid-September into October, things on the coast can be quieting down, but the chances of wet weather start to pick up. But at the same time, the Gorge and adjacent areas like the Hood River Valley can be gorgeous with autumn color beginning to emerge and the harvest season (wine grapes, orchards) is in full swing.

So when would these four day fall, and will you be in Portland for any time before those days or in Seattle for any time after the four? Because other options are possible - day trips to the Gorge or Mount Hood are easy from Portland, and day trips to Mount Rainier are easy from Seattle, as are excursions to various scenic locations around Puget Sound - islands, historic villages, etc.

Have a look at this map - https://goo.gl/maps/AdHrUcqdkiRmWeWo7 . I shows a possible "all of the above" route that could easily be done in four days.

Day 1 - Portland airport to Hood River via the Columbia Gorge (including the most iconic viewpoint) and some waterfalls, such as Latourell Falls and Multnomah Falls.

Day 2 - Hood River to Cannon Beach via Timberline Lodge on Mount Hood (conditions and smoke willing.) You'd see the lovely Hood River Valley en route, and (depending on when this takes place) arrive out on the coast with plenty of time to watch the sunset. (Note, north Pacific sunsets are seldom the glorious ones you see elsewhere.)

Day 3 - Explore the coast - Ecola State Park, but especially Cape Disappointment State Park on the north side of the (awesome) mouth of the Columbia. I've included the town of Ilwaco - a small fishing village - as a possible place to overnight if conditions in Cannon Beach/Seaside/Gearhart/Astoria are full.

Day 4 - Up to Seattle via the Bremerton ferry. This route is more interesting than heading all the way back to I-5, and the Bremerton-Seattle ferry ride will knock your socks off. It's by far the most magical way to enter our fair city.

This would give you two nights on the coast as well as a chance of experiencing the wonders of the Gorge and Mount Hood country. While Google's estimate of 10 1/2 hours' drive time is pretty laughable (I'd guess more like 13 or 14 wheels turning) it's not a very grueling driving plan over four days.

Google the places on the map and think about it.

Beautiful pictures!

Thanks for the info

Looking at this.. Thanks!