One of the best places in the city to get Pad Thai is at Lers Ros on Larkin Street just at the edge of the Tenderloin. Here is a photo of the scene across the street...
Another good place for noodles is On the Bridge in Japantown which serves a type of fusion cuisine called Yoshoku. The Sansei Spaghetti is made with soy sauce and garlic and seasonal wild Japanese vegetables.
For dessert you could go to the nearby Sophie's Crepes for a Japanese crepe with green tea gelato, red bean paste and matcha sauce.
I have yet to try An's Famous Garlic Noodles which are available at Off the Grid on Thursday evenings in Golden Gate Park. While there I had Curry Up Now's Deconstructed Samosa with chicken, garbanzo beans, a mix of chutneys and mini samosas.
Off the Grid takes place at different locations throughout the city, just check the schedule under the links on the right.
All of the dishes mentioned above are both delicious and under ten dollars!