Corte Madera

What is the easiest approach? Last time I tried, 2 years ago, Coral canyon was closed. Is it possible to get in on Corte Madera road? I heard there's a gate. Is there any way to get through it?

You can't go through the north, it's a private ranch.  The Los Pinos road seems to randomly close so you end up hiking from that gate, if you can park, just below the tower.  Even if the Los Pinos gate is open it takes just as much to drive to the junction as to hike, unless you have a badass vehicle you don't mind trashing going fast.  Not sure about Corte Madera Rd but it would take hours to drive all the way around and up that.

 The best option, IMO, is to walk from the CM trailhead. It only adds like a mile to the junction anyway and everyone has to walk from there regardless.  The walk is very nice and very fast, maybe an hour if you're fit.  It is well worth the walk - I've been out three times this season and plan on a few more.  You'll likely have it all to yourself.

Haven’t been super recently but less than a year ago the gate by the fire look out was open. I’d definitely recommend just driving all the way in  through Coral Canyon on Los pinos, past the fire lookout and parking at the Corte Madera Trailhead on Los Pinos unless you feel like hiking an extra 2 miles each way (by parking at the main start of the Corte Madera trail below).  As mentioned, if you try coming from the north right off the 8, there’s a locked private property gate right away. Coming from Corte Madera rd aka Espinosa Trail is a much more difficult 4x4 road.