Something I liked to have a good supply of were Granola Bars (I can't remember the specific brand, but they came in a green box and I haven't seen them in the stores for years). Great energy food; one or two will fill you up for hours, they're great energy food, and take up almost no space -- you can stash several of them on your person. You can easily eat them on a full-speed road march, and you can even munch on them during a patrol. The granola bars they sell these days in the US suck in comparison, and are made more for taste than nutrition; if you want something these days similar in quality, you'll have to pay a premium for items that are specifically sold as "energy bars."
Sometimes, they'll just inexplicably take something good off the market. What ever happened to Captain Crunch with Crunchberries and Tang?
