Oh, how I love my food co-op! We call it Food Fairy (because food magically appears on the dinner table). How it works: there are three families, we each cook one day a week for everyone. The only rules -- no casseroles and no crustaceans (because my husband is allergic). I cook Mondays, one person cooks Tuesdays, and one Thursdays. We have 2, 3 and 4 kids, all about the same ages. I cook on my short or off day from work, and always have dinner on my long day. For one of the other women, it's the opposite -- she's a doctor, so she never cooks on her surgery day.
If you can find a group of like-minded families, I HIGHLY recommend this! BUT, they must be people who not only eat, but parent like you. We all have a "your choices for dinner are take it or leave it" rule for our kids -- no picky eaters allowed!
That leaves one night for leftovers, one night for pizza, and one or two nights to do something quick an easy.