height of wall switches?
I've installed all my switches and even some plugs at 4' - it's a comfortable reach, easy measure and also ensures clearance above any future furniture, cabinets, tables and so on. It's also well out of reach of little ones. And, if you're standard when you do your work, it makes cut-outs in drywall easier to measure for.
At this present moment in time I am making cabinets for the kitchen - just in case you wanted to know what I'm doing when I'm not around.