From what I've been reading on the forum, the weight on your hips will be the last to go (its where your body naturally wants to store it there!).
It seems like you are running around all day with the kids so your body already gets its "workout" so you don't have the urge to do any more. In this case its very easy to get burned out! I would recommend picking a scheme that you can stick with - that is the most important part. If it means you only do weight/resistance training once a week then that is fine!
I only do my resistance training 2-3 times a week and only when I feel like it. I like Mark's free fitness guide (body weight exercises) since you can do it anywhere. Commercial while watching TV? I'll do my push-ups. Also I do shovel glove at least once a week: Shovelglove: The Sledgehammer Workout