My girls' favorite snacks from the time they were old enough to eat finger foods and up include the following; however, check to make sure there are no wheat products in them as we didn't have that problem... I did have to remove sugary items and salty items because our oldest has a heart condition (born with it but controlled via medication and both are children of a diabetic father so we have them tested every year for diabetes and for any pre-cursor symptoms and blood tests for autoimmune diseases since I have lupus (SLE) and Sjogren's disease not to mention other autoimmune diseases that run rampant in my family for multiple generations as I am from a Native American Indian family both maternally & paternally)...
Try peeled cut up apples with cubed (tiny cut) chedder cheese as a snack
Cut up various fruits in a bowl in finger food sizes such as apples, pears, kiwi, strawberries (when in season), bananas, plums, peaches, and etc... Dry toast with a product called Simply Fruit works well too but I would only use that in small amounts because even Simply Fruit, even though it's made from PURE FRUIT, has natural sugars.
Add veggie trays with cut up celery, broccoli, carrots, and maybe even rolled ham slices with a bit of cream cheese in the middle. These are all healthy foods that satisfy their cravings without being overly heavy or causing health problems with regards to obesity. Popcorn puffs are good too. Many specialty stores carry them in low-salt to no-salt options and best of all, unlike popping popcorn, the Popcorn puffs don't have the kernels in them.
Those little 100 cal packs you mention are loaded with sodium and often high fructose sugars. Read the ingredients list and the additional information regarding what's in the products. It's the same with frozen food dinners and lunches including lunchables, which are quick and easy but not so good for the body because of the ingredients and additives. The biggest thing to avoid is MSG. I have to often wonder if many cases of wheat allergies are nothing more than allergies to MSG.
The reason I say this is that once I was able to remove my girls from MSG processed foods then switch them to organic vegetables and fruits, their behavior changed, they began to listen, they rested better at night and took naps without the daily hassle of fighting to get them in bed for their naps, and best of all they were not running around like a kids on sugar highs. Much of this I learned from my oldest child then applied to my last one because there are 10 years difference in their ages. My oldest is now 23 years old and planning her wedding for August 2010 whereas my youngest, who will be a junior bridesmaid, recently turned 13 years old this past January.
I hope these ideas help. I know they have in my home. BTW, if you live anywhere near a fresh food market vs a grocery store particularly in the summer months, check into buying your fruits and vegetables from the fresh food market. You'll find the foods are more healthy, picked closer to ripeness, have a better taste, and more often than not you can find organic foods that don't cost an arm and a leg unlike those in grocery stores. Did I mention the Food Markets by local growers are generally more healthy? :)
Stay as far away from high salt, high sugar, corn fructose, processed foods, and anything with MSG in it. These things have a tendency to bring on not only possible health problems but also behavioral problems that were not present before. Before I forget, my oldest is ADD. She did take the Ritalin and then a newer drug for ADD until she was able to put to use the behavioral modifications our therapist worked out for her. She will be graduating from college spring of next year with her first degree anyhow; and, since she began using her "tools," to handle the ADD and I removed all those hideous additions to her diet, the ADD became more controllable even without the medication using only the behavioral therapy and it didn't put her heart at risk or her overall health.
If I could remove one thing from the foods we have available today, it would be MSG. You would not believe the difference in children and in adults when you eliminate MSG from your diet. It's like living a whole new life - even for me as a mother with lupus (SLE) and Sjogren's disease.
I realize foods are not cheap and many of us can't afford to buy groceries that are healthy; however, Check out this new program that has come out called the Angels Food Network. They offer lots of healthy boxed offers including specialty foods at a low price that is affordable and they take food stamps for those who can't otherwise afford to buy groceries, particularly those in grocery stores filled with the additives we don't need that only make us more tired, cranky, and even more unhealthy. Google the Angel Food Network for your area and you will understand what I am talking about first hand. It's a great program. I've used them from time to time and I wouldn't trade them for anything.
Best of luck...