Buddy, Eugene has several opportunities for you. Try the Amazon Trail (woodchips). It is also called the Adidas Trail. It is marked every 100m. It is by South Eugen H.S. Also you may wan to run on the sawdust trail (bouncy and super on the legs) which is just south and east of the Adidas Amazon trail. I love it.
You could run on the nice bike trails along the Willamette River. Just go to Pre's trail area (Baker Alton Park) by the main bridge.
Also, you can run up in Hendrix woods. Bowerman used to send his boys up there for fartlek workouts. Henry Rono ran up there a few times the one week that he was invited by Salazar to race at U of O. Salazar wanted to break the American 10k record and thought he was in great shape and could put the hammer to Henry. Henry had been 15 lbs overweight, reportedly only two weeks before the 10k race at Hayward Field. Henry did a bunch of hard fartleks up in Hendrix and came down at sprinted away from Salazar that weekend running, if I recall correctly, about 27:31. Go to Nike Town and get some maps of the trails in town.
Have fun. Tom Schwartz