Make picnic lunches. They're fast, easy, cheap - and more importantly, they're fun! You wouldn't believe how much fun Alex has when we have a picnic. He gets involved in the whole process of shopping for the food, making it, and of course choosing the spot and eating it. It's exciting to him! And I will honestly admit: it's exciting for us, too!
Picnics are a wonderful way to save money while still mixing up the typical meals where you sit at a table and stare at the wall.
Also, it doesn't always have to be a sandwich. Bill finds sandwiches to be very boring and I do too sometimes. Plus, Alex isn't fond of cheese. With that said, we rarely eat sandwiches. Usually we have things such as pita wraps, cold baked chicken from the night before, a salad, or soup in a thermos. We also often have the traditional (non-American) Asian foods that Bill makes: ginger chicken, shrimp/chicken/vegetable fried rice, and others.
You're probably thinking, "Yuck. Cold fried rice..." If we need to warm something up, sometimes we'll go to a nearby coffee shop or restaurant and buy a small dessert or drink so that we can ask to warm up our food. Usually they say yes. If we're nearby where we're staying or where a friend lives, we warm it up there. Those friends sure are nice.
"All journeys have secret destinations of which the traveler is unaware." -Martin Buber