What do you want to see in late February and early March?
Do you want to travel I-5 through Medford past Mt. Shasta or turn off on US 199 near Grants Pass and come down the coast from Crescent City?
A winter storm could slow your trip considerably.
I remember a time when I made it from K-Falls to Weed and they would not let me on I-5 without chains. I waited in Weed until they took off the chain restriction (2 hours).
A serious consideration for the winter months would be to take the Amtrak Coast Starlight from Seattle at least as far as Sacramento. The nice thing about the trip is that you arrive in Sacramento before 7AM and then you have breakfast and go find your rental car.

Looks like your first post on Fodor's - welcome!

Of course there's ample time - the drive via the I-5 freeway takes around 12-13 hours "wheels turning" while via the coast route it takes maybe 17-18 hours, so with two weeks you have an abundance of "detour" time.

The good news is that, especially via the Pacific coast, this is one of the premier road trips in the USA, with countless opportunities for stayovers, diversions, side trips and loops, all that.

The less good news is that late February and early March is far from the ideal time for the weather, as it means traveling through some pretty rainy country right at the peak of "rain season."

That's not a reason to avoid it - far from it; it's only a reason to plan a bit in advance. Late winter can be spectacular on the Washington and Oregon (and northern California) coasts. Find some beachfront motel with a fireplace and hope for a storm - marvelous.

Or visit the California redwoods (northern coast between the Oregon line and Eureka/Garberville) when they're at their drippy, misty best. It's really quite wonderful in the wet, provided you're equipped with raingear and have a comfortable place to sleep and dry out.

You might want to block out some time on the calendar - how many days in Seattle proper, how many in SF at the end (assuming the dates are inclusive of both Seattle and SF days) then look at places between Portland and SF that might suit you for a 2- or 3-day stay. The highlights at that time of year are the Oregon coast, coast redwoods in N. California, then the northern Calif. coast along Calif. Highway 1, the part north of SF that gets less press than the more famous Big Sur/Hearst Castle part (south of SF.) But there are umpteen other places in the Pacific NW to visit if time and priorities allow, so some indication of your interests will be useful as well.

We are from the east coast and our daughter is a college athlete who will be playing at the university of Oregon in Eugene not Portland. Sorry for the mistake. Whi knows when we will get back out to that area so any suggestions would be helpful. Is it long enough or to long?

If you are committed to flying to Seattle and returning home from San Francisco, you will likely pay a large drop off fee if you leave your Seattle rental car in San Francisco.
Spend your time in Seattle and then take the morning train (#501) from Seattle to Portland arriving about 11AM.
Rent a car in Portland and drive south to Eugene to see your daughter. If you have the time and the weather is still good, drive down to Medford and east on 62 to the south entrance of Crater Lake. It is truly worth it even if there is snow at the Crater Lake lodge.
Return to Portland to turn the car in by way of Mt. Hood. Take the #11 Coast Starlight south from Portland to Sacramento arriving before 7AM the next morning. There are several places to rent a car in Sacramento if you didn't want to take the YOLO bus out to the airport.
This would avoid driving the potentially dangerous I-5 from Medford to Redding CA.
As Gardyloo says - let us know what you want to see.

Having "done" Seattle, Portland, Sacramento drives and the train ..."tomfuller"gives good advice..
Really depends what you want to do and see....of course the weather is a big factor...I was even delayed on the train one winter due to snow slide on to tracks...we were bused to Eugene..
and sometimes this train is noted for NOT being on time....but the scenery is awesome.....
Personally, I love the Oregon coastal drive...but then again i really like rain.....

I'll tell you all about the "snowslide' traveler24 was refering to. On January 19 2008 at about 10PM, a landslide including mud, trees and about 4 feet of snow took out a long segment of the Union Pacific mainline between the Cascade Summit and Oakridge Oregon. The line finally was reopened on May 3, 2008.
I hid a geocache at the site. http://www.geocaching.com/seek/cache_details.aspx?guid=a579a449-5395-4a01-8afa-167046f98a5c
Check the picture. Amtrak is in no way responsible for delays caused by 'Acts of God' or Union Pacific dispatchers.
On a sad note a female freshman of the U of O drowned at Summit Lake (SW of Crescent Lake) on Sunday. There are much better places to swim and Kayak on Crescent and Odell Lakes.

I would probably use the time to explore Washington, Oregon. For example,
Feb. 26-March 2: Seattle - you could spend 2-3 days in Seattle and a couple of days in an overnight trip (or two nights) to a surrounding area such as Olympic National Park, The San Juan Islands, Victoria by ferry, Mt. Rainier (ski, hot chocolate etc), wine tasting in Woodinville.
March 3-7: Portland/ Eugene, then head down to Portland to visit that city, wine country, visit daughter.
March 8-12 (Oregon Coast) head out to the Oregon Coast and explore from Astoria south as far as you want to go, returning to Seattle for rental car drop off and flight home. We loved our stay in Seaside/Cannon Beach area. Further south is lovely too. I recall a wonderful little sandwich shop in Manzanita.

The Pacific Northwest is a gorgeous area, even when raining. Also, you can set your itinerary based on your interests - do you want to get outdoors, go hiking etc, or are you more interested in art galleries and antiques, or do you just want some great food and wine experiences. All of these are possible in the great PNW -- Just dress appropriately.

If your heart is set on the Seattle-SF drive, you could take the above suggestion and turn the March 8-12 section into a drive down the coast. At some point you will need to cut over to an inland route to reach SF by the 12th. We usually do the whole Seattle-LA drive in two days but that's taking I-5 and limiting stops to food, sleep and with cooperative weather. The coast is much longer and so much more to see and enjoy. The redwoods north of SF are also very cool and make for a good overnight. You could just plot a course on the coast and head south allowing for 4 overnight stops and just see what you see along the way, with interesting stops scheduled for lunches, shopping, enjoying amazing views and local color. Lots of great lodging, B&Bs along the way to add to the road trip experience.

We travel from the Seattle area to Fairfield, CA (north bay) at all times of the year. We take the coast route to avoid the Siskiyou Mountains and because it is far more scenic. Slower...but nicer.

It is a beautiful drive and as stated, the weather is a factor. I would do it but come prepared with warm clothes in case you have to spend some time in the car sitting on the freeway. On the other hand, I-5 is really open most of the time with only occasional closures.

I live in Eugene- what sport will your daughter be playing. If you need Eugene recommendations, let me know

Thank you so much for all of your suggestions. My daughter will be playing lacrosse at the Univ. of Oregon on March 4th and 6th so we will have a few days to explore in and around Eugene.

For a coast trip from Eugene, head west on 126 to Florence and go a few miles north to see the Sea Lion Cave and Heceta Head lighthouse. If you have even more time you could head back south to Reedsport and head east on 38 to see the elk at Dean's Creek.

Heceta Head lighthouse is under construction for major repairs and it is totally covered up - however it is still a beautiful beach, there is a nice trail up to the lighthouse- and beyond if you choose.
The lighthouse keepers house is a B&B so if you want to treat yourself, check into staying there for a night- they have an amazing breakfast in the AM

pkg,

Because you are from the east coast, you should definitely take the opportunity to make the whole trip from Seattle to San Fran.

Because your likely image of Seattle and Portland is rainy if anything at all, you won't lose much for seeing both in the rain.

If you landed in Seattle on Feb. 26, it would make sense to stay until the 28th, and then drive to Portland for a couple of days. Perhaps on the afternoon/evening of March 2, you might drive west, to the ocean, to spend the night somewhere on the northern Oregon coast, hoping for clear weather the next day as you drive south toward Newport or Florence where you'd drive east toward Eugene (arriving there on the evening of March 3)

On March 7, you would set off to the south and alter your route depending on the weather near the Oregon/California border. IF there is snowy/stormy weather, then you'd make your way back over to the coast for the trip south (perhaps catching the Redwoods along the way). If the weather is passable then maybe you'd opt for the Interstate path perhaps as far as Redding, Red Bluff or Williams, CA, from which you'd have options of returning to the coast for a scenic path toward San Fran.

If, say, you arrived in San Fran on the 9th-ish, you'd have 3 days there before flying home on the 12th.

Hope this makes sense.