Just a random place to drop Marin hikes for now. More great hikes over at http://www.marintrails.com/
Mt Tam on the South Side
Places to start a hike (or bike) to the summit of Mt. Tam, via Railroad, Gravity Car, or Temelpa.
Hill 88 from Fort Cronkhite
A bunch of folks were also working on a restored portion of the Nike missile site near here, I haven't been but there are supposed to be tours on some Sundays. Also, there's a Marine Mammal center here I keep missing, and, if you look carefully (they do their best to camouflage it), you might see the Golden Gate Raptor Observatory folks with their blind, capturing and banding hawks.
Pantoll to Rock Springs
I first laid out this map using Google Maps, and couldn't figure out the right route. Now I clearly need to re-hike it, or you can just look at where the paths go on the OpenStreetMap layer.
I can't figure out exactly where the trails are from the satellite view, but they're fairly self-explanatory. Don't miss the wreck of the 1940s era car. Recently someone drove off Bolinas Ridge road and landed within 20 feet of the wreck of that car.
Also, note the top of Cataract trail. During the winter this is a fantastic hike, it starts down near the Alpine Lake dam if you want to do it up then down.
Bear Valley to Arch Rock
I'd have to carry a GPS with me to locate Arch Rock, but there are maps in the visitor's center. If you take a bike, take a lock, you can bike to within about a mile of the coast. Watch for albino deer (the park service is currently trying to remove them), and if you get to the coast and haven't found the rock yet, look to the stream to the south of you for the trail down to the arch and the beach.
McClure to Kehoe
Ultra-hardcore, to be done only by experienced hikers with wilderness rescue experience, and it takes a fairly heavy minus tide and a willingness to get wet. Get a copy of "Point Reyes Secret Places and Magic Moments" and follow the instructions, and you might have an experience like our 2008-06-08 McClure To Keyhoe or our 2011-06-18 McClure to Kehoe hikes.