Not sure I concur with "best track in N. America"... Willow sounds a lot like
PIR up here. Relatively flat & about 2 miles, but ours is 12 turns with the chicane. A well set up GT3 or the like get's into the 1:20's.
For a more technical experience
Oregon Raceway Park is akin to a roller coaster with many of the turns blind going in, and
The Ridge is somewhere between - fast
and technical...
Pacific Raceway Park is the old school course with lots of ways for your day to go wrong...
We're kind of spoiled up here. All of the these are within 3 hours of Portland. PIR is 15 minutes from my house...