We've done nearly all the hikes around Telluride and this may be the gem of them all.
The Sneffels Highlight Trail is a long-ish 15+ mile loop on the north side of Telluride. It starts and ends at the Jud Weibe trailhead, climbs up over a pass at over 12,000 feet and takes you through thick pine and aspen forests, wide-open alpine meadows, past crashing waterfalls and gurgling streams, up steep grades and along flat traverses. Most of all, this trail has scenery. Bring your camera and plan on being awestruck. You'll get great views of Telluride and the ski resort from way up high.
If you're a trail runner and are feeling fit, the entire trail is runnable though a couple of sections are steep enough you'll be hiking. To run the trail, go clockwise as this makes the ascent more gradual. To hike it, consider counter-clockwise and get the climbing out of the way so you can have an easier stroll for most of the hike.
This is a long hike so be prepared. Bring a lunch and plan to stop for a while and enjoy the break. Bring extra nutrition, too, in case this takes longer than you expect. We did this hike in about six hours hiking without hurrying and we took a break for lunch. We could see it taking much longer if the weather didn't cooperate or if someone got sick or injured. We didn't see many people--probably half a dozen the entire day, a Sunday in August.
We were spent but happy when we got back. We sat down in the San Miguel river in town and (somewhat painfully) chilled our legs; we recovered quickly and were good to go the next day.