The Boy Scout Trail near Glenwood Springs will take you through thick forests, over cattle fields, and along ridges. There are some areas where you can get really good views of the city below. <br />
This trail doesn't loop all the way but it does connect to the same road, and it's possible to hike back up the road to where your car is. This is a multi-use trail so please use caution.
The "legal" way to do this trek is to ride up Red Canyon Road on your bike or a shuttle. To do this take Highway 82 South towards Aspen until you get to Buffalo Valley/Beau Jo's. Hang a left on Red Canyon Rd and go up almost 2 miles. This route is 2 miles. The preferred route is to take Doc Holliday's trail up through a small stretch of private, meeting up with the Boy Scout. To get to Doc's take a left on 13th off of Grand/82 and then left on Bennett. The trailhead is well marked.
http://www.tripleblaze.com/trail.php?c=3&i=837