This sandwich fits the bill perfectly.
You can prepare it in the morning, wrap it in a long piece of foil, and refrigerate until it's time to toss it into the cooler and go.
Remember to pack a sharp knife, as this sandwich needs to be sliced at serving time. It will easily feed 6 people or even 8 with a little macaroni salad or some chips on the side.
It's our favorite and I think you'll agree it's just right for picnics!

1 (1 pound) loaf French bread, halved lengthwise
4 tablespoons butter, softened
2 cloves garlic, minced
1 cup grated Parmesan cheese
1 head lettuce, shredded
1 pound sliced cooked ham
1 pound prosciutto or mortadella
1 pound sliced salami
1 pound sliced Provolone cheese
2 tomatoes, sliced
1 sweet onion, sliced
1 (10 ounce) can pitted black olives, sliced (optional)
Preheat oven to 425 degrees F. In a small bowl, mix together the butter and garlic. Spread garlic butter on both halves of bread, and sprinkle liberally with Parmesan cheese. Place in preheated oven until cheese is golden brown, about 5 to 8 minutes, remove from oven and allow to cool slightly.
On the bottom half of the bread, place a layer of lettuce. Alternating between meat and cheese, arrange layers of ham, prociutto or mortadella, salami, and provolone. Add a layer of tomatoes, onion, black olives. Place the remaining half of bread on top.
Place the sandwich on a cutting board, and slice into individual servings.