Road Trips:
(Whidbey/Deception – Anacortes) Take the ferry to Whidbey Island. Drive north to Hwy 20. Take 20 north, stopping at Ebby's Landing for a walk on the beach and stopping at Deception Pass to take photos. The sandy beach and turquiose waters at Deception Pass State Park are popular. If you are here on a weekday, I'd skip Ebbey's Landing and stop at the park. Continue on Hwy 20, through Anacortes, to I-5 and drive back to Seattle.
(North Cascades – Methow Valley – Leavenworth) Or, if you have 2+ days: continue on Hwy 20 east of I-5 through North Cascades National Park (DEFINITELY worth it - allow lots of time). You can stop and tour the Diablo Dam... From the park, continue on Hwy 20 to Mazama and take the dirt road up to Harts Pass (6,800'). The view from the pass is AMAZING. There are signs at the lookout that label all of the North Cascades peaks. After Harts Pass, continue on Hwy 20 to Winthrop (can camp at Pearrygin Lake - good swimmin' hole). Winthrop is a neat, Old West style town (kinda touristy). Keep going east through Winthrop toward Hwy 97 and follow the Columbia River back to Hwy 2, then west toward Seattle.
(Snoqualmie Pass – Leavenworth – Stevens Pass) I-90 to Cle Elum, 97 north to Hwy 2, stop in Leavenworth. Hwy 2 west over Stevens Pass, back to Seattle. There's a shortcut in Monroe that get's you back to town faster, but I don't have my map in front of me.
Mt. St. Helens Take a road trip to Mt. St. Helens Johnston Ridge Observatory – impressive view!
Mt. Rainier Take Hwy 410/123 to the Stevens Canyon entrance of Mount Rainier National Park and drive the park road (stopping at Paradise) to Longmire, then back to Seattle.
Olympic N.P. – Hurricane Ridge/Obstruction Drive to Hurricane Ridge, Olympic National Park and take the dirt road to Obstruction Point – amazing views!
Neah Bay Drive out to Neah Bay – the most northwesterly point in the Lower 48. Take a side trip to Shi Shi Beach – you’ll thank me later. (see below)
Mt. Baker You can take 542 out to Mt. Baker, but there’s not much sightseeing along the way until you get to the lookout at the end of the road, but what a view! You could do this as a side trip on the way to/from Canada, though…
Some of my other favorite stretches of highway are heading west through Chinook Pass and heading west toward Mt. Rainier from White Pass. You could make a loop of these two passes and take a drive through Tieton country…
Just some ideas off the top of my head…

[This message has been edited by Pierce County Ag (edited 8/13/2010 4:26p).]