Instead of buying pre-assembled bags of trail mix at the store, try making your own at home. Not only is it a fun activity for the kids to participate in, it allows you to control the salt and sugar content. If you're up for it, you can also make your own granola. A great source of fiber, granola can also be high in sugar if you buy it at the store pre-made.
In addition to granola, tasty -- and healthy -- ingredients include dried fruits, various nuts, unsweetened coconut flakes, peanuts, mini pretzels and pumpkin seeds or hulled sunflower seeds.
HINT: If you're not worried about the added sugar, kids will love the addition of M&Ms or chocolate chips.