Okay so I have an Office that I’m modelling, its currently scaled to 2.74meters. When I start adding additional rooms and furniture, what is a good rule of thumb to keep everything scaled and proportioned correctly? Is there a better way then just eye balling it? I don’t want a scene that can have both elves and giants in it 
You could probably use the doors for size comparison.
If you make sure you have your units (in the scene tab) set to meters, then you know that 1 Blender Unit is 1 meter. After that you know exactly how big everything is.