Whenever anyone visits San Francisco, there are just some places a tourist must strike off the list. The Golden Gate Bridge, Fisherman's Wharf, Ferry Building, Lombard Street, Alcatraz, Union Square, cable cars, ...
And if you have time, Coit Tower, Twin Peaks, Castro, Golden Gate Park's gardens, oldest/largest Chinatown in the US, ... etc. etc. etc.
But why did noone ever mention Lands End to us??
Now that is really a gem. A beautiful trail with intense views and peppered with little bits of history: ruins of baths, shipwrecks, old rail tracks. Quaint little trails that branched off the main path, some with rudimentarily cut out steps winding into a secret-garden-esque landscape, some leading to treacherous-looking spurs overlooking the bay, some leading to quiet little beaches. Windswept and misty and lush and fairytale-like.
Even if you're not a hiker, this is worth a visit, no question about it.