I'm in a similar situation, visiting for a few days with my bike in tow.

On calmarchris' recommendation I did my own version of that Elfin Forest ride; just finished it actually.
Quite nice, mostly rolling hills with a few short sections of stomach-punch climbing with trap-door descents over the crest.

http://connect.garmin.com/activity/15601813

If I had known where I was going, I would have explored more around the El Camino del Norte section. It looks like some fun, low-traffic riding into that hill.