The Hoo-Koo-E-Koo. Fun to say and even more fun to hike. Dogs are allowed on-leash.
There is flat fire road with expansive views of Mill Valley as you enter. This in an of itself is an excellent place for a low-impact walk. Then the Hoo-Koo-E-Koo trail itself, accessible from two ends of the fire road, is an invigorating climb with a spectacular payoff. At the top you reach a crest with views of Mill Valley to the East and Mt. Tamalpais park to the west.
(Note: This is a popular area for mountain bikers.)