The fair place to meet is Portland, OR — the city closest to the midpoint of Sacramento and Seattle. From the farther side that’s about 10 hr 8 min of driving.
Recommended midpoint
Portland, OR
From Sacramento
10 hr 8 min
483 mi to Portland
From Seattle
3 hr 38 min
145 mi to Portland
Seattle has the shorter trip; the split is off by about 6 hr 30 min. The alternatives below can even it out. Sacramento and Seattle are about 625 miles apart.
Sacramento and Seattle are about 625 miles apart by road. Split the difference and you arrive near Portland, the city closest to the halfway point between them. That puts roughly 10 hr 8 min of driving on the Sacramento side and 3 hr 38 min on the Seattle side — the fairest single meeting point among the cities near the middle.
That's a half-day drive from each side, so Portland suits an overnight or a weekend rather than a quick coffee — long enough to want a reason to stay, short enough to drive.
If Portland doesn't have what you're after, Boise and San Francisco are also close to the midpoint and worth a look — each keeps the drive reasonably balanced between Sacramento and Seattle.
Portland is the most populous city in the U.S. state of Oregon. Located in the Pacific Northwest at the confluence of the Willamette and Columbia rivers, it is the 28th-most populous city in the United States, sixth-most populous on the West Coast, and… Read more →
Sacramento is the capital city of the U.S. state of California. The county seat of Sacramento County, it is located at the confluence of the Sacramento and American Rivers in the Sacramento Valley. Read more →
Seattle is the most populous city in the U.S. state of Washington and the Pacific Northwest region of North America. Read more →
City descriptions adapted from Wikipedia (CC BY-SA); photos via Wikimedia Commons, credited above.
Estimates use straight-line distance and typical road speeds; real drive times vary with route and traffic.