Colorado in the fall
Billings, MT to Buford, WY
From Billings, Denver is about a 7.5-8 hour drive but I BEG of you - if you are ever in a 500-mile radius of Buford, Wyoming, PLEASE look up Chas and Gail's beautiful property and stay there for the night.
Chas and Gail settled down next to a national forest and built two tiny houses and a campsite to give people the opportunity to see their beautiful way of life. Their property has multiple ladders over the fence line to explore the surrounding national forest. If you have the chance to stay during a meteor shower, do that too. From hammocking during sunset, to losing count of shooting stars, to a campfire during sunrise - their property has the most magical feel to it.
The next morning we drove down to Rocky Mountain National Park - less than a two-hour drive.