You can also think about the Moab Skinny Tire Festival in Utah. It's an easy drive nfrom Spokane, and the festival is fun riding in Canyonlands, they get 600 to 900 riders. The road rides are 4 days, and other things to do are hiking in the National Parks and explorering the area. There is also a showing of the Banff Film Festival in Moab that week, an added bonus. It is March 12 - 15.
http://skinnytireevents.com/content/section/4/141/