Using an electric knife or sharp bread knife, slice each loaf in half lengthwise.
Spread cut side of top of each loaf with 1/4 cup mayonnaise; spread cut side of bottom of each loaf with 3 tablespoons mustard. Line bottom of each loaf with leaf lettuce; top lettuce with half of tomato slices.
Arrange meat slices and cheese slices evenly over tomatoes on each loaf, alternating meat and cheese. Top each with remaining tomato slices, and cover with tops of bread loaves. Slice sandwiches and serve.