Look at the trails near Ouray/Silverton/Telluride. Nice drive from Denver.
Look at them on a PC, much easier than a phone. They have pretty good ratings and make sure to read the reviews (some are one way, better in a certain direction, require a winch, etc). Scenic to moderate to difficult, and a lot depends on current weather and time of year. I go out there a few times/year, 3 trips this year.