I crossed 50 through Colorado in late September (don't remember which year). There had already been a snowfall, as snow was piled up alongside the road from plowing, but it was clear when I went through.
I use US-36 across Missouri all the time, coming home from Michigan. Traffic is much lighter than on I-70, and the rest stops and overnight stops are well-located for where I am at what time of day, going in that direction. Eastbound I sometimes us US 54, for the same reasons: moderate traffic, stops fitting my schedule in that direction.