US 2 in central Washington is quite nice, although hot in midsummer.
US 2 west of the Cascades is quite challenging.
If you are interested, I can give you more details.
Starts in Mukilteo at the lighthouse park.
Snohomish River Road has light>moderate traffic.
Snohomish-Monroe Rd. has significant commuters during rush hours.
Use
caution on Wallace River Bridge on US 2 E. of Startup.
Reiter Rd. and Index are sweet - with some great views.
(Avoids some very dangerous bridges on US 2)
US 2 narrow with guardrails and a short tunnel to Skykomish.
One more tricky bridge on US 2 E. of Sky .
Then a great stretch of the Old Cascade Hwy.
After that you can continue climbing on a rougher stretch -
Or take a wide, but busy US 2 over Stevens Pass.
(BTW - US 2 has twice as much traffic on weekends - all of Seattle)
(Worst time heading east - Fri. afternoon, Sat. morning)
Once you get on the east side US 2 has fair shoulder and less traffic.
Swing over to camp (?) on Lake Wenatchee.
Then back roads almost all the way to Wenatchee.
Some of the early apples and pears should be coming in - - yum!
Nice bike trail along the Columbia River.
Then a hefty, but gradual climb on US 2 to the Columbia Plateau and Waterville.
By now, US 2 has fairly light traffic and shoulders, too.
Camping on the lake at Coulee City.
Definitely worth the 2 miles south on Hwy 17 to Dry Falls overlook - esp. in late in the day.
Continuing on US 2 - light traffic - the old Almira Hotel, and the collapsing Govan schoolhouse.
Stock up in Wilbur, last good sized town for a while. Grocery store on west side of town.
Miles Creston Rd. to Fort Spokane, light traffic, roller coasters, but more down than up.
Hwy 25, light traffic, continues north along the Columbia to Kettle Falls and the NT.
Jama
https://ridewithgps.com/routes/47806339.