Nothing against egg salad on spongy whole wheat, but the textural difference between dry bread and juicy fillings is one of the things we love best about sandwiches. Susie Cover, a former caterer and private chef and a mother of two, has figured out how to prepare the standard lunch food the night before and still have it taste fresh. Her first choice for bread is a wrap; she finds whole wheat or whole grain versions keep best. She also likes a hearty baguette or ciabatta. But bread alone won't combat mushiness. It's important to keep any sauce—like honey mustard or pesto mayonnaise—on the side. Cover packs the sandwich along with a container (these test tube-like vials are perfect) of sauce that you or your child can dip the sandwich into as you eat. Another idea, straight from the streets of Nice in southern France: Make a pan bagnat, a tuna sandwich that actually improves the longer it sits.