Our Family really loves hiking in Marin during the winter, especially when there's a waterfall involved. One of Marin's favorite family hikes is at Cascade Canyon Open Space Preserve near Fairfax. The trail here winds through Elliott Nature Preserve, along San Anselmo Creek, to the 20-foot Cascade Falls. It's particularly popular during the winter and spring when the creek is flowing, but it's a great place for a fun family hike at any time of year. This easy out-and-back hike is about 1.5 miles round trip.
Start out at the trailhead on Cascade Drive in Fairfax and head onto Cascade Fire Road. San Anselmo Creek burbles along to your left, and you'll find a couple good flat spots for the kids to walk down and explore the creek. Ordinarily you'll follow Cascade Fire Road for approximately a half mile until it meets with Cascade Falls Trail, fording shallow parts of the creek in a couple spots.