Bay seniors don’t have to fight the traffic and the clock to get to coastal trails. 20 minutes north of the City, the 1.7 mile Tennessee Valley Trail is broad and flat and with each step you amble closer to the broad black beach cupped in the Marin Headlands and its postcard-ready view of the Bridge. If you plan to picnic make sure you are far enough from the water’s edge. This is the Golden Gate and the surf can gallop up the beach suddenly. When the tide is low you can see the engine of the shipwrecked SS Tennessee. There is plenty of wildlife and foliage, notably fennel and blackberry bushes, For the non-acrophobic the recently rehabbed trail west to Muir Beach offers high drama from its cliffside panoramas. No dogs darn it. Free.