I plan on going to Sitgreaves nation forest in AZ from Durango CO....I will take either 191S in AZ or 491S in NM down to I40...which is the easier drive for my underpowered Yoda??? ...tia
Both US191 and US491 stay out of the mountains as they head south to I40. In this area the mountains are a NS range right along the state border.
You'll encounter more mountains as you enter the National Forest. In this part of the country, forests cover the mountains. The open country between the mountains is too hot and dry to grow trees.