This is one of my favorites, with incredible organization and a great experience from check-in finish. You will like the swag bag (it's a potato sack), the pre-race pasta dinner, and the post-race food. The race itself is wonderful, featuring wooded trails and a run through farmland.
The marathon course was absolutely beautiful, transitioning from cool conifer forest to rolling Idaho farmland. Heartbreak Hill in Boston has nothing on the grueling uphill from mile 17 to 20, but the rest of the course is downhill and fast, with a nice mix of surfaces.