Steep Ravine, Matt Davis and Dipsea are among the most enjoyable trails I've ever done.  I started at 8am from Stinson Beach.  The hike is pretty strenuous from the beginning, but absolutely gorgeous too.  A ton of waterfalls, that neat ladder you have to climb up is a lot of fun.  Part of the hike is a fire road but by then you are seeing views of the water and San Francisco.  The peak is one of the most fun, you can see the city, the ocean and the east bay.  The hike down was a typically peak climb down, it's pretty for the most part, but the real scenery is on the way up!  A lot of fire road going down.  Once you hit the campsite it's a little confusing but I made it.  The last 4 miles to Stinson seems to never end and has some rocky footing, but by 4:30pm back at Stinson with the sun going down, it was among the most rewarding experiences of my life.  Without this challenge I don't think I would ever have tried Tam.