Pinwheels can be prepared ahead of time either cooked through and then served cold or cooked on the morning of school and added to a warm food flask. They are the perfect alternative to a sandwich. Switch it up using different cheeses (just make sure they melt like a Cheddar).
Bagels are usually only served freshly toasted. But I have a genius way of keeping them warm in our food flaskbut not letting them go soggy. Why not change it up each time by choosing a different combination of spread and toppings.