Thanks Craig,
 I definitely want to get a glimpse of the desert as I have heard a lot about it. I think it will make a nice compare and contrast to the rain forest and illustrate to us firsthand how the mountains create the rain shadow.
 
 I hope our focus on the coast doesn't sound too myopic, we both grew up on the east coast and practically lived in the surf in our youths. I've been to the Pacific before but I can appreciate that my wife hasn't and I remember what it is like to see the west coast for the first time. That's what she wanted to do this year... heck otherwise I'd go back to Maine and see all the friends I made last year. :-)

Hi,
 
2 ways to think about it.
 
Fast and Slow!
 
Fast. Straight down I-5, and then take 199 in Grants Pass. Also a nice drive and it gets beautiful green just south of Eugene, all the way to Crescent City. You can stop in Grants Pass for refreshments, and then an hour plus to Crescent City, and the Redwoods.
 
My favorite place in the world!
 
Slow. Drive Highway 126 all the way to the coast and then go down the coast all the way to Crescent City on Highway 101. Very beautiful drive and you will want to stop and take pictures, specially if you are on a hot date!
 
If you fly into Portland, you should also plan on spending a night somewhere and then call me, or Craig (if he's being hospitable) and we can have a nice evening doing nothing and more nothing and sweet buck'all nothing, and just enjoy a good yap ... I might even take you guys to the Brazilian Restaurant!
 
Portland is nice, but it is a really big small town and its tastes are almost exactly like a small towns.

Thanks Mosh,
 We'll be coming through in August. Time is going to be tight.
 
 I was just looking at grants pass on the map.

We are figuring out that Cannon Beach is the beach and we're rolling in just before Labor Day weekend.
 
Yikes!!!
 
Looks like we might have to head south ASAP.
 
 

mike_mccue
We are figuring out that Cannon Beach is the beach and we're rolling in just before Labor Day weekend.
 
... 
 

The best (and less popular) campgrounds in the Redwoods are usually already closed by that time. The 2 big ones, should be fine, and I think the one on 199 is open almost all year around.
 
Too bad the timing is too tight ... would have gladly joined yah for some fun yapping!

Camp grounds sound perfect for my wife and I, but with our mom we are going with clean beds and separate bath rooms so she can be relaxed.
 
So far we found some rooms at a BnB on a beach about 10 miles north of Humbolt Redwoods State park and just south of Redwoods National Park. That will be our primary "base camp".
 
We also just booked some simple rooms at a small lodge just outside of Crater Lake National park so we can spend a couple days. When we leave there to return to Portland airport we are going to go out to the desert and come in through the Gorge and make that a long day trip.
 
Now I just have to find two one night stops on the way down to the BnB on the beach. All the stuff on the coast up near Portland has 2 and 3 night minimums but as you head south we are finding more one night opportunities.
 
I keep having an urge to see Astoria and the Columbia delta but I also think I'll dislike driving through Beach Town scene on the last days of Summer... I can do that right here. :-) Is the landscape around Astoria worth the trouble?Maybe I am over thinking it... down here Beach Town scenes extend for 100 miles and traffic moves at a slow crawl. Maybe it's a lot less intense up there?

On your way to Crater Lake, there are some really great sites right off the road.  One is where the river runs through some beautiful rock formations - a must see.  We found these just by keeping our eyes open on the way.  We took the ranger bus tour at Crater Lake.  You can't get down to the water from the top but the view is awesome.

Thanks for the tip Jimmy.
 
I'm trying to keep the driving schedules short enough to allow for plenty of surprise stops and minor detours. :-)
 
A guided tour at Crater Lake seem like a great way to make it easy for mom to have as much fun as we are.

craigb
As you go east from Portland the Gorge (as it's called) is really stunning.  There's a very distinct change when it goes from the rainy area to desert area too.

Specially Multnomah Falls!
 
Crater Lake is strictly a visit and look-see place. But it is beautiful to look at. The whole thing is very similar to other spots in Eastern Oregon, like Wallowa Lake. There are also many spcial spots off Highway 395 from Umatilla, all the way to Reno. That drive from Klamath Falls to Reno (specially) is one of the prettiest EVER ... and only the portion of the Columbia Gorge between Portland and Hood River, is competition!

Have lived on the west coast all my life...
 
As has been mentioned, head east along the scenic route for the Columbia River Gorge (you exit from the freeway as you leave Portland).  There are several fabulous waterfalls along that route, Horsetail and the well known Multnomah Falls, to name two.  Crown Point has a nice vista of much of the gorge.
 
Astoria is good, or take just about any of the two lane roads over from the valley to the coast.  A stop at Gold Beach is another option, the sand dunes at Florence might be of interest, and Depoe Bay is a very tiny and quaint place.  On the way back, if you take the route from the coast back to Grants Pass, a stop at the Oregon Caves could be fun (one of the larger cave networks outside those at Carlsbad, NM.  Overall, IMO, US 101 is far more scenic that I5.  If you like Victorian architecture, the Carson Mansion in Eureka is worth a look.  Jedediah Smith Redwoods and Redwoods National Park, as others have mentioned, are almost "must" stops.  If you like more-or-less dirt roads, consider taking a detour to fern canyon on the coast.  Also if it still exists, Lazio's in Eureka has very good seafood.  Crater Lake is futher east than it sounds like you might be going.  Bend, on the east side of the Cascades is a jumping off point for much of the scenery in eastern Oregon.  If you like wading in the ocean, the beach at Seaside is unusual for a west coast beach in that you can wade quite a ways out into the ocean.  Note that Seaside and Cannon Beach are popular tourist places.
 
As for "rain forest" you would need to head north up to the Olympic Peninsula.  The Olympic Peninsula is unique in that it contains a temperate rain forest.  The Hoh River Valley averages something like 175 inches of rain a year.  IIRC, the only town in the area is Forks (sorry, no town named Knives or Spoons).
 
Anyway, have fun.