When it comes to sandwiches, the world of flavor combinations is endless. From classic to creative, there are an array of popular sandwich fillings combinations. Topping the list are bacon, lettuce and tomato; ham and cheese; grilled cheese; Italian cold-cuts and cheese; and egg salad. Whether you top the bacon with mayonnaise or keep it simple with just tomatoes on your grilled cheese, these five fillings allow for variation while ensuring a delicious experience every time.