Eastern WA you have Lake Chelan, or for real remote Stehekin is awesome but look into the ferry. I don’t know the Palouse valley as well but some incredible places out there.

See if you can get up to the Islands, all are amazing but reserve a spot at Moran St Park for a while. The park books out 6-8 months in advance. It’s worth it. Trails, Mt Constitution, swimming at the lake.

Port Townsend was mentioned, defiantly check out the Hoh forest.

Also look at the Columbia River. Starting down at Vancouver WA and winding up east bound. Little towns on both sides of the river. Shout out to Backwoods Brewery and Pizza in Carson WA.

Seriously I would look at traveling around in a circle, either direction and plan out the different areas. With weather these days I’d look at being on the coast for late July/August. Look at eastern wa for fall and nice weather through September start of October. Then maybe islands and peninsula for winter. You’ll get lots or rain but winter storms are also beautiful and cozy if your set up for it.