I would love to be able to see how long the wait times are for MTO orders from an Android or iPhone App. Now that you have a mobile app, please consider adding this. For instance, the mobile app for Great Clips shows how many minutes the wait time is for all of their stores. Your app would show how long of a wait it is at any particular store for MTO purchases. This would help redirect people to less busy stores.
Have two limited time bistro style sandwiches available per month. Example, a turkey pesto caprese sandwich on multigrain bread and a vegan option like a beet and lentil burger topped with apple slices, sauerkraut and Dijon mustard on rye bread. I think the veg option is important and if well advertised will draw in a lot of customers.