I find the lunches here are not great food choices and when I was really sick I found out that the little middle bought a baked potato and that is all she ate every day for lunch, potato and cheese. There are a lot of fatty choices that they just don't care for. (We aren't perfect or health nuts just don't want burgers, nuggets, pizza or other junk food every single day).
When I am feeling good and have the time I make them bento lunches which they and all the other kids love (even the ones who work) they are fun and just by their nature lead to a wide variety of choices. There is a link on my blog to our food blog (Loon-atics in the kitchen) if anyone is interested that has our recipes as well as our bento making experiences. The bento lunches can be hot, cold, room temp and you really don't need the fancy containers a tupperware or rubbermaid or even the dollar store divided containers all work.
Everyone LOVES these, their friends have offered to pay us and buy supplies etc but I usually just make extra for them to share so not always cheaper depending.
Otherwise to keep from boredom we try to do things like wraps, bagels, pita, salads and even hot things in a thermos.