If you have a family on the run, you probably grab a lot of quick meals at kitchen bar.  

A counter bar is at the same height as the countertop (36 inches high).  "The Rules" recommend giving each person 24 inches width and 15 inches depth minimum to eat comfortably.  I'm not big on minimums, so I prefer to add 3 inches to both those because there’s often other stuff happening like surfing the web on your laptop or doing a bit of homework.