From Seattle it is 30 -35 miles to the track. I'm going out all day Saturday, don't know what day you are going to try and go. Like Rick S. says go early, as HWY 18 is backed up from both directions of people trying to get in there. I only live about 7 miles from the track and I always go thru Auburn, up past the Green River College and then cross over HWY 18 to the entrance. It's alot faster then sitting along the shoulder of the road creeping along slowly.
Where are you working in Seattle, I'm going to be going to the Seattle Center for our sanction vote tomorrow morning?
Let me know what day your going out to the races, maybe we can meet somewhere and go in together. The gates open at 8:30, I'm planning on being out there a little before then, will be staying all day to watch the Sportsman class's run.