Avoid Seattle all the time. Avoid INterstate 5 between Olympia and Everett as much as you can, especially on Fri afternoon.
I drive up there every year at least once to see family. I usually stay on the east side of the Cascades and drop into Seattle from I-90 over Snoqualmie Pass.
YOu have to drive around Puget Sound, unless you want to take a ferry.
You could drive from Glacier to North Cascades on US 20. Then go south on the east side of the Cascades to Yakima and visit Mt Rainier via Naches and White Pass. From there leave the Park and head southwest to I5 near Olympia. From there head to Oly Peninsula.
