Left or right? (Or, Design considerations for public facing restrooms)

When designing and building restrooms in public facing spaces, for example at a restaurant or a gas station, there are many things to consider. How many stalls and/or urinals, how many sinks, paper or air dryers, etc. Some of this, I’m sure, is dictated by public law, some by architectural standards, and some (I hope, anyway) is determined by the artistic and aesthetic desires of the designers themselves.

Having been at a few places over the weekend, I noticed something else about the design of these spaces that hadn’t occurred to me before: in some places, the Men’s room was on the right, and in some places it was the Women’s room that was on the right. And some doors open in, some open out.

Which got me wondering:

What is the decision-making process that goes into deciding which restroom – Men or Women – goes on the right, and which goes on the left? Which door opens out and which opens in? And what about those occasional “family” restrooms, what goes into the planning for those in terms of their placement?