We serve chicken wings, pizza (cheese, pepperoni and sausage), chips, dips, cookies, occasionally fruit or cupcakes even, three or four different types of $5 footlongs, coke, sprite, water and diet coke. Never can tell what anyone will eat, but everyone can find SOMETHING that they'll eat. The wings are comped from The Crowbar in exchange for copies, the pizza's comped in exchange for copies, and the $5 footlongs aren't all that much. Everyone's well fed, always left overs to nibble on when you're not on set or even after filming.
Oh, and always put the mayo, mustard, salad dressing on the table, not the food. And make sure that not all the sandwiches have cheese on them. Easier to keep all day, and in case someone has some dietary restrictions either for health or religious reasons.