Impossible to say w/o knowing how many weeks you have.

Oregon and California are VERY big places (especially California). So where in Oregon do the relatives live? And are you interested in any of the thousands of places in CA that are not in LA?

It is too much. Have you looked at the map? It takes about 10 hours to get from Seattle to San Francisco without stops on I-5. You don't see anything, but just drive. I guess it depends on how much time you have, if you have a month or more, then it is doable.

The most direct highway route between Seattle and San Francisco is 808 miles. To make this journey in 10 hours you will have to drive at an average speed of 81 miles per hour--and make not stops.

HTtY

If you choose to drive a rental car plan on 2 or 3 days on I-5 to return the car to Seattle where you rented it.
A drop off fee will negate any savings you may get by flying home from LAX.
You really ought to see more of Oregon than the I-5 corridor. Plan on a bare minimum of 8 days.
The other option is taking the Coast Starlight at least part of the way and having at least 2 rental cars.

THanks all - we have 2 weeks. I am interested in seeing northern CA too. LA is a wish list... We were thinking of trying to do it all at once. Family is in Portland. We would spend a few days at least with them.

I disagree that it is too much, with 2 weeks. This makes for a great road trip.

We are from L.A. and we've done this both by car and via the Coast Starlight. Both have their pluses and minuses.

Between Portland and Los Angeles, to do it up right, you should spend at least a week from point "A" to point "B".

Highlights for us in Oregon -- well they were all pretty amazing -- was Portland itself, a wonderful and liveable town (we're going there tomorrow for the weekend, in fact!); Eugene (one of the prettiest college towns I've seen); Crater Lake (my husband and I still talk about the starry night sky there, and how it was the best star watching we had ever seen!).

In California -- either the route from the east, down Lake Tahoe; Yosemite; to L.A. is a nice way to go. Or through Sacramento, to San Francisco, then the coast route down through Monterey is another.

All in all, plenty of photo ops, plenty of good fun!

No - 2 weeks is not long enough. A 'few days' in Portland, a couple of days on the OR coast, northern CA, and Los Angeles (and I presume returning to Seattle) would take 3 - 4 weeks.

W/ just 2 weeks, this time stick to Seattle, Portland, a bit of the OR Coast, maybe Crater Lake, and maybe the redwoods in far northwestern CA. That would fill your 2 weeks.

Some other time - spend 2 weeks seeing LA, the CA coast, SF and maybe Yosemite (that would more than fill 2 weeks)

Didn't see surfergirl's post. IMO it would certainly make a doable 'road trip'- in other words a driving tour. But not a visiting or stopping over trip. Especially w/ your few days in Portland. Even if you only mean 3 days there - that only leaves 11 days to go all the way to LA and back to Seattle -doesn't leave much time to stop/detour/visit places.

First post from a new Fodorite. Without knowing how much time they have, it's impossible to give quality answers.

Portland and Seattle are only 4 hours apart on I-5 so consider flying to PDX seeing the family and then renting the car for Seattle and perhaps Mt. Rainier or Mt. St. Helens.
Coastal Oregon is better than coastal Washington as far as tourism and scenery IMO. Consider stopping at Crater Lake NP and Yosemite NP. You can always fly to LA on another trip.
LA sure does not have the attraction to me that Yosemite does.

Gardyloo: "Without knowing how much time they have, it's impossible to give quality answers."

In the OP's second post s/he says they have 2 weeks.

Doh. Missed it. Sorry.

As for the main question, it depends on travel styles.

2 days in Seattle, 1 day to Portland via Mount St. Helens, 4 days in Portland including one to Mount Hood and the Columbia Gorge, then 2 days driving to SF via the coast and Redwoods, 1 day in SF, 1 to LA via 101, and the last 3 in LA. Sure, it's a bit rushed, but totally doable. It would obviously require a one-way car rental, but that would be necessary in lieu of driving all the way back to Seattle, for which there wouldn't be time.

We spend 13 days in just Oregon in 2010 and 10 day in just Washington this year. Frankly, we didn't even scratch the surface.

LA is one of my least favorite places in CA. I really like San Fran, San Diego, Yosemite, Sequoia, the drive along the coast(Montery/Big Sur area),Pt. Reyes, Northern California(redwoods, lassen national park) far far better than LA. I like Death Valley, but wouldn't suggest it in the summer.

You all have been tremendously helpful. We have a lot to think about. Thank you.

You can easily spend 2 weeks in Oregon and still not see all of the 7 tourism regions. http://www.guidetooregon.com/regions/index.html
Why rush around trying to see 3 states in 2 weeks?

That dead link was really helpful - it speaks very highly of Oregon.

If/Because you're coming from the east coast, you really should do what you can to see what you've always wanted to see.

Furthermore, because you'll be in California for plenty of time, there is reduced need to see the Oregon coast on such a trip, thus letting you cover Oregon a tad faster than some might.

IF the mentioned drop-off fees become obstacles, you might consider flying from your home to Portland, and renting a car there for/after time spent with family, then driving north for a round-trip to visit Seattle - Mt. Rainier on the way up, and Mt. St. Helens on the way back??? (maybe leave Portland to the east, and then go through the Columbia Gorge, and then north via the path between Carson, WA and Randle, WA, enroute to Mount Rainier {visiting Paradise or Sunrise there} and then on toward Seattle via the east side of Mt. Rainier)

Upon return to Portland after your time in Seattle, then take a TRAIN from Portland to San Fran, where you could rent another vehicle, for a southern "loop" including L.A. and back to fly home out of San Fran. That for consideration mainly in the event that rental car one-way fees are too costly. You'd also price the airfares to the various combinations of arrival-departure destinations as well, seeking the best match between airfare and rental car prices.

IF you drive between Portland and San Fran, the main Interstate (#5) is fastest, but some would drive eastward toward Bend, in central Oregon, and then south from there seeing Crater Lake along the way. Others might drive down the coast most/all the way, and still another option is to drive any combination of I-5 and/or Hwy 97 (from Bend) and then cut to the coast from Grants Pass, OR.

With two weeks you can give it a good, solid effort, and perhaps not get the fullest effect of L.A., but you could at least touch the reasons why you always thought you wanted to see L.A. in the first place. (nothing quite like walking around the Hollywood Walk of Fame @ 3:22 in the morning, just because it was the only time you could fit it in) (you can sleep on the plane ride back home!)