The out and back hike is about 3.5 miles depending on who you ask. It's got over 1000 feet of elevation gain though, and it's quite technical. In summer heat it's pretty exposed to the sunshine, but in the winter it's wonderful to be warm outdoors. Not to mention the great views over to the ocean! There's even a little section of scrub oak forest which always makes me pull out the camera.
We did the two rounds in about an hour each, and felt like we got a nice workout. A good change from the treadmill workouts I've been confined to lately.