You've got lots of options!
Last Summer, I hit Penitente Canyon while passing through. It was short but way fun--well worth a stop. If you like techy stuff, you could kill a whole day there just sessioning rock features Since then, I have added some "must do's" from the area to my wish list.
Check the link below. Deep Creek and Middle Frisco loop particularly good:
http://www.southforktrails.com/
From Del Norte, you're not far from Pagosa Springs--see link
http://www.pagosatrails.net/
The Cat Creek trail looks nice (written up in the Mountain Bike America: Colorado guidebook)
You're also within striking distance of Taos (South Boundary, Devisadaro, etc).
As previosly noted, it's an easy jaunt up to Salida. Pretty much year round riding and in late summer, the Monarch Crest is not to be missed!
There's a whole mess of other potential routes. Get the FS maps of the area. Also check out Trails Illustrated 139, La Garita Cochetopa Hills and 142 Pagosa Springs.
Have fun--I know I would!