There are two approaches I've used.
In particularly complex places, I've actually copied the "you are here" exit maps, and drawn in my circuits - using different color high-lighters for different areas.
On a lighter note, in one building I labeled office circuits, describing the office location in terms of it's geographical location. However, since the hall ran north/south, the offices were divided into 'east' and 'west' groups. This had the unintended result of there being a 'mid-west' office ... and a 'mid-east' one as well.
