Housework is the first to go for me, too. Some weeks all my house time goes to the 2 chores that take up the most time and are most immediate, laundry and cooking/kitchen cleaning. I don't know what the answer is.
When I finally do have some time, the last thing I really want to do is clean. I'd rather cross other things off my to do list, things that STAY done and don't need to be repeated a few days or a week later. I have the summer off (preschool teacher), but next fall I'll be working a day more than I did this year. Something will probably have to change then--maybe we'll look into hiring a cleaning service, or maybe the kids will have to take on more.