I'm most in agreement with the person who alluded to the definition of "scenic". The amounts of dramatic mountain backdrop would limit you to the crossings of the Rockies. The inclusion of greenery can put you into a problem spot--like where somebody mentioned the Blue mountains, which are incredibly green but with scenery that is blocked out by a tree funnel. Donner has this problem in a lot of places--and the more open areas have limited access. I'm kind of biased with the Washington scablands too only because I'm out there so much and know know where to go. I would have to put CP's Windermere Sub between Ft. Steele and Golden, BC at the top of my list and the Crowsnest Pass line, Marias Pass, mid and upper Columbia River Gorge and parts of the MRL right behind. I also love to shoot the ex-NP between Billings and Glendive, MT.