Options for Washington State portion of west coast trip

Four middle-aged adults are planning a June trip to the west coast. We will arrive in Seattle, rent a car, and visit Washington state, the Oregon coast, and the northern California coast, then depart from San Francisco. We have established our routes in Oregon (mostly coastline) and in California (Redwoods, Napa Valley, and San Francisco). In Washington, we are interested in Seattle, Mt. Rainier, Mt. St. Helens, and Olympic National Park, but we are having trouble deciding on a sensible route to include these stops. So my questions are: 1) What IS the most sensible route to drive to these places? 2) Is the coastline in Washington a must-see, or should we cut inland in order to make the most of our time? We have 12 days to drive this route, but would like to spend a day in Seattle and 1-2 days in San Francisco.
Thanks for any advice!

Welcome aboard the RoadTrip America Forums!

There are a few ways to try to fit in everything you want to see in Washington, but I think what I'd do is spend my day in Seattle and then take a ferry across Puget Sound to Bainbridge Island and drive to enjoy the northern and eastern parts of Olympic National Park. Then head south on US-101 along the Hood Canal to Olympia, the capital, and then use some smaller roads WA-510/WA-702/WA-7/WA-706 to Mt Ranier National Park. US-12 west back to I-5 and then WA/505/WA-504 would get you to Mt St Helens. But if I were under any time constraints, I'd drop this side trip to Mt St Helens. By the same token, if you're going to be spending time on the Oregon and northern California coasts, you can skip the Washington coast as slightly redundant. You should have plenty of time to make this work for you.

AZBuck

We did a route around Washington State a few years ago. You can see it on the following link
http://www.uk-2-usa.com/Routes/washington.html

You did not mention the Northern Cascades which I would strongly recommend - look at the photos on the pages linked to from the above link.

What I now regret is not fitting in Olympic National Park. If I were to repeat this trip, I would probably get the ferry from Whidbey Island across to visit Olympic rather than to Everett and the Boeing factory

We initially included North Cascades in our plans, but we weren't sure we'd have enough time. We definitely want to include Mt. Ranier, Mt. St. Helens, and Olympic, and have enough time left to meander down the Oregon coast with a few days at the end of our trip for Redwoods, Napa Valley, and San Francisco. Do you think including North Cascades would be realistic for a 12 day trip? Also, do we need reservations for the Washington State ferries, or do we just need to arrive at the terminal a bit early?

You could certainly 'fit' the North Cascades into your itinerary in 12 days, but whether it would be worth it is a call that only you can make. Everyone has a different travel style from the frenetic to the laid back. Personally, I'd try not to go adding too much more to what you already have planned, but if you're comfortable with more driving and less time on the ground, then suit yourself. That's the beauty and responsibility of RoadTrips.

As for the ferries, if I knew when I'd be crossing, I'd go ahead and make a reservation. Even if I waited until the day before, I'd call to make one. If a particular crossing were full, at least I'd find it out ahead of time and make a reservation for the next available boat. It's just too easy to make a reservation, even late, and too much of a time sink to wait around because a boat was full not to make sure I had a place on the next boat leaving when I arrived.

AZBuck