Deer Creek
Deer Creek is a cool little trail. To get used to the altitude or as an intro to D-Ville area technical trail riding it's a good place to get started. Taken as a loop from Packers Lake it provides a good workout from the steady climb up to and along the saddle down along Deer Creek and back to your car. Some local riders refer to it as "trials" type riding in its complexity.
If you don't have time for a full-on expedition one day, come up here. You'll have a good, high altitude workout and get your minimum daily requirement of "hard-rock" riding excitement.