Trying to plan a menu...

I have always wanted to plan monthly menu's for my family. I have tried and failed many, many times, but I keep trying. I know that it would make my life, with 5 kids under 9, easier, but "things" have always come up. The "things" that interrupt my perfect(haha) plans are normal everyday if you have kids these things happen, sickness, unplanned guests, forgetting to take out the meat, a forgotten activity, or mom just not wanting to do it. I know what I have in my freezers and cupboards, and know what I can throw together, so there is always something for dinner. I just wish that dinner would be a little more organized. One of my goals with summer here is to plan a menu for 1 month at a time, I'm hoping getting out and written down someplace it can't get lost will help me stick to the plan.