Seattle

Route
Day 1: From SeaTac, WA 99 North, WA 516 West, I 405 North to Kirkland.
Day 2: I 405 North, WA 525 North, Mukilteo/Clinton Ferry, WA 525 North, WA 20 East, WA 20 Spur West, Anacortes/Lewis/Orcas Island Ferry, Orcas Rd to Moran State Park. Local Roads, Orcas Island/Shaw/Anacortes Ferry, WA 20 Spur East, WA 20 East, I 5 South, I 405 South to Kirkland.
Day 3: I 405 South, I 5 South, WA 504 East, WA 504 Spur East and back, WA 504 East to Johnson Observatory. WA 504 West, WA 505 West, I 5 North, I 705 North to Tacoma. I 705 South, I 5 North, I 405 North to Kirkland.
Day 4: Local Roads, WA 520 West, I 405 South, WA 167 South, WA 512 West, Local Roads to Washington State Fair. WA 512 East, WA 167 North, WA 516 West, I 5 North, I 405 North to Kirkland.
Day 5: I 405 South, WA 520 East, I 5 South, Local streets, WA 99 South, Local streets to West Seattle. Local streets, WA 99 North, Local Streets, WA 520 West,  I 405 North to Kirkland.
Day 6: I 405 South, WA 520 West, Local Streets, WA 202 East to Snoqualmie. WA 202 West, Snoqualmie Parkway, I 90 West, WA 519 West, Local Street, WA 519 East, I 90 East, I 5 North, WA 520 West, I 405 North to Kirkland.
I 405 North, WA 525 North, WA 525 Spur North to Boeing.  WA 525 Spur South, WA 525 South, I 405 South to Kirkland.
Notes
WA 504 (Spirit Lake Highway) is one of the magnificent drives from WA 504 Spur (Old WA 504) to the Johnson Observatory. 
Results
Counties: WA: Cowlitz, Island, San Juan, Skamania, for a new total of 1052.
Clinched WA 20 Spur, WA 504, WA 504 Spur, WA 525, WA 525 Spur. Mileage on I 5, I 90, I 705, WA 20, WA 99, WA 167, WA 202, WA 505, WA 512, WA 519.