Paul:
I think the term that you seek is forced perspective, using smaller scale objects further back in the layout to give an increased sense of distance from the viewer. In the photo below, our Chrysler building and Empire State building are made from 3-dimensional jigsaw puzzles and are probably about N or Z scale. They are positioned about 5 feet from the front of the city section of this portion of the layout. Though they are greatly out of scale with the Department 56 city buildings, they appear to be a greater distance away giving the scene more depth.
I hope this helps.