You might want to consider getting the
Mountain Pass DirectoryThis would allow you to check different routes, easily.
In general though, any "US" route (vrs State Route) would be OK. There are exceptions, like Alt- US-14 in Wyoming, but those are covered in the directory.
Now if -you- would be OK is another question. Example traveling east bound on the Going to the Sun road (Glacier Park) can be just plain scary to people that aren't used to driving along a cliff. On average the Rangers have to drive someone off that road every week. They get on the road and freak out