In the Mission, now as terminally hip as it was formally poor, the St Francis is a greasy good time since 1918. Stuck beautifully in the 50's both aesthetically and menu wise it's Americana in a bun. Dig in.
If you can get past the bourgie factor and/or you work down the street like I do, you will come to love this place. It has some of the best food in the city, a Blue Bottle coffee, and an observation deck from which you can watch the ferries come and go, emitting their weird beeps and disgorging tourists. The people who work here are great too (whether or not I dated a baker from the Acme Bread kiosk because of a Craigslist missed connection will be left to history).
Murals! where? everywhere! walls, streets, signs, windows. keep your eyes peeled. I walk a lot in San Francisco and always seem to find new murals in the least expected places. They are a constant source of inspiration, and make me wish I could paint worth a damn.