Competition

The Ozark Trail 100 Mile Endurance Run is a point-to-point 100 mile ultramarathon on the Ozark Trail through the Mark Twain National Forest in south central Missouri. 
http://www.ozarktrail100.com/

The Heartland course is ran on the seemingly endless prairie in the beautiful Flint Hills of Kansas where National Geographic Magazine's published an article and pictures of the Tallgrass Prairie, where the Heartland 100 Spirit of the Prairie run is located.
http://www.ksultrarunners.org/

Situated in the visually stunning Marin Headlands just north of the city, The North Face® Endurance Challenge Championship course has surprised runners with both its scenery and amount of elevation change. Participants are encouraged to train for repeated uphills and downhills of several hundred feet at a time.
http://www2.thenorthface.com/endurancechallenge/races/2009/ca/index.html
A majority of the course covers run-able fire road (very little technical single track) overlooking the Pacific Ocean with occasional glimpses of the Golden Gate Bridge.

An ideal course layout for elite speedsters and those taking their first strides in the world of trail ultrarunning, the Endurance Challenge Madison course is run-able from start to finish, provided that you’ve trained hard enough. Located 60 miles east/southeast of Madison, in the southern reaches of picturesque Kettle Moraine State Park, a large portion of the course takes place on the renowned Ice Age Trail.
http://www2.thenorthface.com/endurancechallenge/races/2009/wi/index.html
The forested area, massaged by monstrous glaciers many millennia ago, contains wake-up-call hill climbs of 200-300 feet and enough undulating terrain to challenge even those granite-legged mountain runners. Overall, the soft, forgiving course is 80% singletrack, with slightly wider, equestrian sections sprinkled in between. This is the least technical of all the Endurance Challenge courses.