Also summer is the time for road repair and construction. Always fun to wait and wait to go a few miles at a time. I suggest checking your route for this and plan.....particularly with fires near Yakima and I-90 construction. However this has much improved over time.
I have to pitch Astoria. What a great spot right on the mouth of the Columbia. A must stay is the Canary Pier Resort, awesome and worth the price. It has great views of the ships, a great restaurant and spa, and they will drive you in a choice of Roll Royce or other classic cars into the town for free so you do not have to park. its crowded there for a reason, but then i like the beers (both Bouy and Fort George) and particularly Pilot distillery which makes the famous Painted Lady Gin. No tax there, so its 1/2 price of WA.
OK so I have lived here nearly 70 years and a little biased having been everywhere. For an outsider I agree north Olympic peninsula, Crescent Lake, and Dungeness Spit county park a must see. Hike a few miles of spit out into the straits of good old Juan De Fuca.
Leavenworth, is busy, but great food and brews, and representative selection of great WA wineries tasting rooms. Don't miss Larch, a great dining and cocktail establishment. Parking is a bit tough in the summer, but we stay at friends summer home and walk into town. Icicle Creek nearby hiking and camping, and then head over to Lake Chelan and stay at the old Cambells lodge at the end or new airbnb's, you can even stay in a party pontoon boat and cruise the lake. Drive up to the North Cascades and stay in Early Winters, the ski resort that never happened. Great hikes and mountain bike trails.
Go take a look at the Grand Coulee Dam, but don't take the wrong turn and end up at the base of the dam like we did in 1964. My Dad missed it.....
You can loop back from Hwy 2 going down Hwy97 to I90 and hit Suncadia and Roslyn. Fun little town with some great food like authentic Mayan cuisine, The Brick Saloon is across the street, or stay at Suncadia and enjoy the golf and winery and dining there. Off roading, you can go up to the top of some really great hills with open views of the east side mountains. Hit Snoqualmie Falls and stay at the lodge there with an excellent breakfast. Get your Costco gift card and save a few bucks on the package. The falls are a big hit for most to see.
Then there is Walla Walla versus Woodinville, both have many of the same wineries accompanied by some great dining options. White House in the walls, and Barking Frog or Delille in Woodinville, but we like Russell's, casual and high end chef and a secret discount 2 for 1 with a Passport app. Heritage is very good as well.
If you do Anacortes check out LA Conner, named after their famous politician, at least a local fav.