Floor plans are a great way to convey not only the size of a property but how it will work for the viewer. They quickly show where rooms are in relation to each other in a way, visually, which the viewer quickly understands.
Here is an example of the same property as both a 2D floor plan and as a 3D floor plan. The 3rd example is a 3D floor plan with (example) room descriptions (callouts) added.
2D Floor Plan
3D Floor Plan
3D Floor Plan with Descriptions
More 3D Floor Plan Examples