Protein, in any form, will give you better sustained energy. Carbs, even complex carbs, are converted into sugars before the body can process it, so that can leave you with a sugar (carb) crash. Fats give you a lot of energy per gram, but it takes longer to convert, so they're better for long, steady distances. For the "best bang for the buck", a breakfast of oatmeal, orange juice, milk and eggs. Lunch and dinner, think pastas.

Machka mentioned Nutrition Data before. There is a really good feature where you can input what foods you ate and the amounts and it will analyze it for you and give you the results. Very helpful, indeed.