If you like Japanese noodle soup, I would definitely check out Katana-ya. It's right near Union Square on Geary/Mason. My favorite is the chicken soba.
@MarsinAries It's funny you mention Osha. I live right across the street from there and my old roommate works there too, lol! It's pretty decent, but I like Lers Ros more (Larkin/Ellis) OMG it's so delicious.
Back to the OP: and if I were you I would definitely check out one of the specialty gelato/ice cream places in the city. Either Bi-rite Creamery near Dolores Park, Humphry Slocombe in the Mission, or Holy Gelato in the Sunset. Honey Lavender, Golden Beet, Blueberry Cabernet, omg the list goes on