The chicken wrap sandwich at Pecos Bills is very big and comes already cut in two. It comes with fries and you can even get cheese sauce for them at the toppings bar. With all the stuff on the bar (including sauted mushrooms, sauted onions, lettuce, tomato, pickles), you can essentially add a salad or side dish to your meal, too. I think two people can easily have a filling and satisfying meal there with one entree.
At any of the counter service meals, you can order a large drink and ask for an extra cup, too.