Ab training doesn't have to be overcomplicated, in fact It can be and for me is very simple. I train my mid section once a week upon completing day four of my H.I.G.T program. ( Day four is the full body monster set day ).
My abs have just been worked hard during the training with exercises better than any crunch. Squats, dead lifts, pull- ups and other multi joint exercises. Your abs must contract hard to stabilize your core in order to correctly perform these exercises, so they have been worked over pretty good. Again better than any ab machine, I promise you!
I finish them off with six sets of a combined three very distinct weighted exercises from very unorthodox angles. Kneeling rope crunch, oblique and inter-costal super set, finishing with some sort of bridging exercise. Simple and effective. Look I am thirty seven and just an average guy with the same domestic responsibilities as you. Family, work & overtime, home and travel. You just need some basic planning, smart eating strategies and a goal. Good luck.
Richard