I never visit a city without a map. I rarely use my GPS. I admit this would have been useful in Tokyo, where everyone gets lost, even people who live there. But tracking down locations via the Magical GPS Goddess also means I would have not had the experience of discovering unexpected places. 
As I always tell my private tour guests, when you use a map, you get a sense of place. You learn how the city is laid out, and where sites are located compared to each other. Look a map, and you can see that Coit Tower is about a 20 minute walk from Chinatown, and Chinatown is on the edge of Union Square. Golden Gate park is on the western side of the city, next to the Haight Ashbury.
You don’t learn this by punching in a location, and having the blue dot direct you. You only learn what is on that path, and not where that path is in relation to the rest of the neighborhood or city. Plus you’ll be staring at your phone and not observing what is around you.
A GPS has its place in travel. If you’re hideously lost, it helps. But unless you find yourself in a strange wilderness (which means you’re probably in the Presidio), use a map. Ask directions of people on the street. Travel is about experience, and you lose some of that adventure by allowing the Magical GPS Goddess to lead you by the nose.
Get a map. Ask directions. Occasionally get lost. That’s how to experience San Francisco.