Ok boys, time to brag up your favorite "putts". List the highways if possible, I've riding for a little over 15 years now and have covered a lot of ground out here in the west. I really can't put a finger as to my most favorite road, mainly because we have some serious seasonal changes out here. You don't want to be caught on top of Bear Tooth pass in October or anywhere in southern Utah in July or August!
So with that said I think my favorite spring time ride is the "lochsa" (locksaw) Hy. 12 out of Missoula Mt. down to Orofino Id. the caution road says "winding road next 77 miles". It is loaded with properly banked twistys and some wide sweepers, lots of game, deer, elk and every once in a while a grizzle bear. This is a fun run in both directions, just do it in the daylight!
A fun summer run is "the Bear Tooth Pass" Hy. 212 from Cooke City Mt. (northeast gate of Yellowstone Park) to Red Lodge Mt. The pass takes you up to 11000 ft elevation, lots of little alpine lakes, the only palce that I've ever looked DOWN and seen mountain goats!
You can also access "Chief Joseph senic Hy. 296" from the western base of Bear Tooth Pass, cool story about that route. (signs on the summit tell the story) From there drop down into Cody Wy. and check out Bill Codys firearm museum, give yourself 4 hr. minium.
Then there's always Glacier National Park up in northern Mt., Logan Pass (Going to the Sun Road) is a must see at least once in your life.