My girls (6 and 9 years old) loved the quesadillas at Wolf Gang Puck Express. We went for breakfast there too, and they don't have a kids menu for breakfast so they could order anything. One got the chocolate chip waffles and the other got the breakfast pocket which was eggs, bacon, mushrooms, peppers and cheese baked into a pizza dough. They loved it! We went to WPE three times during our trip because we all loved the food there.
Earl of Sandwich is good too for kids. The girls each got the grilled cheese sandwich - it looked to be the same size as the adult ones and they really enjoyed them.