My go to place is Good Mong Cock, 1039 Stockton Street. This is a great family run take and go chinese bakery. The steam pork buns are not only huge but,in my opinion the best in Chinatown. Huge variety of dim sum. No single item here will set you back more than $1.50. Great bang for your buck.
There are a million places. If you want good and cheap pizza on the run, you can go to Blondies on Powell street. This is a place to get a huge piece of pizza for next to nothing. If you take the cable car to Chinatown, Grant Place on Washington Street is really kid friendly with good and inexpensive chinese food. It's so cheap, the kids can try different stuff for very little money. In North Beach, there is Il Pollaio. This place has really good roast chicken, sausages.. Not too expensive and kid friendly. There is also Mario's Bohemian Cigar Store. Good Italian sandwiches. This is my kids favorite sandwich place.My only suggestion to you is not to eat anywhere on Fisherman's Wharf or Pier 39. The food is gross and expensive.
Grant Place is Great!! for Noodles in the afternoon. Duck over mein is fantastic. When I say cheap, I mean you can eat great for about $7 with tip. Their dim sum is not bad. Lychee Garden is on I want to say Powell. This is a real chinese place. Really good Wor won ton soup. Crab with black bean sauce is really good and not too bad a price. If you want really cheap eats in Chinatown, stroll up and down Stockton Street during the early morning and afternoons, this entire strip is loaded with chinese bakeries (char shu bau and law mai gai), take out only shops, and markets. This is the area where local people go to get the food. Stockton is one street up from Grant . It's a great area to eat for under $5.
----- Grant Place 737 Washington St, San Francisco, CA 94108
The R & G is a really good chinese place. It's up-scale enough to satisfy your stuffy friend. For me this place, though the food is good, is a little over-priced. You can find food of this quality cheaper at the Lychee Garden which is just a few blocks away. Though this place does not have the upscale chic of the R & G. It's just good family style chinese. By the way, if you decide to go to the R&G do not let them seat you downstairs. This is the area where people with kids generally are seated. It's more cramped and loud in this area
----- R & G Lounge 631 Kearny St, San Francisco, CA 94108