Oh yeah, some more details.... If you get there before the beginner's race you'll have plenty of time to pre-ride the course. There tends not to be a lot of time between races to do this, as the back of the field finishes well after the front.
The October 24 Willamette Valley race is going to be on a defunct golf course. I did this race last year, and it was very fun -- very flat, grassy (obviously), went through a couple of sand traps.
The October 25 race is at the Washington County Fairgrounds. It's also very flat. Last year it was insanely muddy, and I would expect that again this year. It went through a rodeo arena, which was so sloppy that those of us in the lower classes had to run the entire length. See photos here:
http://www.flickr.com/photos/2638250...7609330193445/
Astoria -- I don't know anything about the course, but I hear this is lots of fun. One race will be a costume race, so come prepared. Here's a video from last year (I think -- YouTube wasn't responding so I can't verify):
http://www.youtube.com/watch?v=OnDCpUdF8JY
I don't know anything about the other two.