Idaho is pretty cool. I lived there for a few months and went up and down it. I didn't get to ride much, or at least I didn't go to any places that were that good, but it seems to have potential. Tons of public land and some big mountains/high elevation. Dusty, dry, high altitude desert type stuff in a lot of the state. I did a lot of camping, hiking, swimming and wading through streams (I mean, I was working for the Forest Service). For that kind of outdoor stuff, it's awesome.
I like Boise too. Neat little city with some cool stuff but not too big.