Steamboat is the main eastern handoff
Northwest Canyon Country is centered on Steamboat Springs and the road west toward Craig and Dinosaur. Denver, Boulder and Fort Collins should not stretch this region back onto the Front Range.
State Forest State Park is the deliberate exception. It sits in North Park and makes sense in three guide regions at once: Northwest Canyon Country, Central Mountains & High Country, and Denver / Front Range & Pikes Peak. The overlap is useful for trip planning even though the regions are not administrative boundaries.
More driving. More space.
Northwest Colorado asks a little more effort and gives a lot of room back. Dinosaur National Monument is the big developed dark-sky anchor, while Steamboat Lake, State Forest, Craig-area astronomy and western reservoirs add camping, water and long self-guided nights.
Farther north and northwest, the BLM country of Moffat County reaches modeled Bortle 1 darkness. This guide treats it differently from a normal destination: it is a broad public-land dark-sky watch area, not a single telescope pin, and visitors need to stay well away from active oil-and-gas operations.
Let Steamboat become home base
Steamboat is the place to reset, fuel up, sleep and decide whether the next night points north toward Steamboat Lake, northeast into State Forest, or farther west toward Craig and Dinosaur.
Dinosaur is far enough out that it can become its own destination within the region. Northern Moffat dark country is more remote again and should be planned as public-land travel rather than a casual roadside stop.
Watch the fuel gauge as much as the sky map
Farther northwest, the distances stretch out. Fuel, weather, campsite plans, land status and road conditions deserve a look before you leave the last easy stop.
This is not the branch for discovering at 12:30 a.m. that the next open gas station is a very long way behind you.