middle point

Hello everyone, just wanted some advice on a fairly simple procedure that I am always finding myself having to find a work-around to do on the go. 

Say I wanted to put a toilet between two wall partitions at exactly half way between both walls. Since the half/division marker is only created for the entire length of wall, previously I would have to either draw a line between the two points and snap to the line's half way point, or measure the distance, divide by two, and go off one of the two points. 

What is the quickest/easiest way to get a snap-point along a straight line/wall, exactly half way between two objects that connect to that line/wall? 

Thank you in advance.