So it turns out, in our house, our planning horizon is about one day. Therefore, our one-week iterations were consistently having problems: lots of dropped tasks, but still very busy. As well, the effort of trying to maintain a huge backlog revealed some environmental constraints: we spend a lot of time on yard work, for example.
As a result of these two discoveries, we have moved firmly to day-long iterations. Each day at the beginning of the day we take between 5 and 15 minutes to plan out our days TODO list. Melanie and I each have separate lists. We coordinate our lists throught the master household backlog. Melanie does very well in choosing a TODO list that she can accomplish in a single day, partly because she uses her daily planner to schedule things (estimation). I tend to have a lot of small things fall off the end of my list at the end of the day, mostly because I do not do any sort of estimation or scheduling. I may start.
In my previous entry about Agile Household Management, I mentioned the use of a corkboard. That is no longer being used for tasks. It is now being used for general notices and lists relating to larger tasks. For example, a list of items we need to purchase from Ikea, and a list of repairs we need to hire a plumber to do. My iteration (daily) TODO list is now a piece of paper at the side of my desk.