If you're looking for an easy scenic walk that offers mountains and a well-maintained flat and low rolling hills trail, leading to one of California's iconic Pacific beaches, consider the Tennessee Valley trail to Tennessee Beach in Mill Valley, CA. Just a few miles north of San Francisco, it's an easy to get to walk in splendid nature: about 3.4 miles round-trip path out and back.
From San Francisco I took Golden Gate Transit #4 bus over the Golden Gate Bridge to downtown Mill Valley, where a friend picked me up for the short drive to Tennessee Valley trailhead. Lyft, Uber, and cabs should be accessible, though there's not much cell service in the trail area, so make arrangements.
Tennessee Valley is an off-shoot of the Marin Headlands. For more information, click here.