Lower Hunter Creek Trail is a 1.7 mile trail that features a river and is good for all skill levels and connects to Smuggler trail with a beautiful viewing deck above the town. The round trip takes about 5 miles in 2h. Bring water and energy bar.
If you'll be driving from Denver airport this will be on the way. It's a beautiful scenic route that is just asking you to stop, get out of the car and take some pictures. You'll be driving through the town of Leadville which contains many historic structures and sites in its dynamic mining era. Stop at the "City on a Hill" Coffee shop to get some drinks and homemade goods and if you have time stop at some amazing thrift shops for vintage treasures.
There are plenty of beautiful bike rides around Aspen like Mclain Flats, Ashcroft, Maroon Bells and Snowmass. Most of them are moderate to difficult so it's good to have a chat beforehand with the local bike tour guide mr. Ron Schreiber, he will advise what's the best ride to take.