Sounds like you are getting a lot of good suggestions! We have a lot of the same issues, though no kids. My boyfriend is celiac and very health-conscious with a very high metabolism (so we need a lot of calories!). He eats a lot of chips, but even that's a lot cheaper than, say, beef jerky (one of his other faves). I buy them when they're on sale, because it's not like chips go bad (at least not until they're open).
But we also have a lot of cheap, tasty, easy snacks that we love, like popcorn, roasted chickpeas, and pan-fried rice cakes. We don't each much fruit, which I think helps a lot with the food bill, but the fruit I do buy I'm pretty price conscious about - cantaloupe is super-cheap this time of year, apples will be dirt cheap in a month or two, orange prices drop over the winter. And apples and oranges keep in the fridge for weeks.
It sounds like you're in a pretty rural area, which can make groceries very expensive, so definitely think about making a few stock-up trips a year. Head down to Portland or wherever is easy for you, and stock up on things that won't go bad. You might even be in the range where keeping a chest freezer makes sense (my uninformed impression is that a lot of people end up spending more on electricity than they save on food, but YMMV).
