Hwy 55 from Boise to McCall is winding canyon for the first section, the after your climb up to the Round Valley, it's wide open and fairly flat after that except a short climb and downgrade north of Cascade on Little Donner Summit.
If you go around on Hwy 95 through Weiser, Cambridge and New Meadows, then on over to McCall, it is a bit longer and about the same in climbs in short sections. When we head up there, we always go Hwy 55. It's scenic, but watch the other drivers. A lot of people like to speed through there and there tends to be quite a few accidents. In just the last two weeks there have been three.