About a month ago I checked on bus service from Durango to Denver- looks like you have to take Roadrunner transit from Durango to Grand Junction~6hr for ,$45, then you take Greyhound from Grand Junction to Denver~5.5hr, for $64. ~ 11-12hr and $110 total.
But you can get a rental car from Durango airport to Denver Intl. (DIA) for ~$90 and thats ~a 7-8 hr drive if you take HWY285.
I’m in the same situation- Im planning to Drive to Durango mid june -park the car somewhere (its $7/day at airport or at the narrow gauge RR parking lot in Durango) then rent car to get to Denver to start the trail. Unfortunately the long term parking is pricy.
I know that for me, flying into denver then renting a car to get back to DIA is cheaper than driving out to Denver- but I plan on doing some car camping after the trip.
This is the info I gathered from forums and web sites- if anyone knows of a cheaper way- or if this info is incorrect please let me know
Danl