Jon,
Calumet is a great choice for a freelance effort when choosing Chicago. As a native Chicagoan, I freelance my layout with a Chicago theme too. It is easy to model a whole bunch of road names because so many railroads came into Chicago. In fact, as you probably know, Calumet is not the only location where multiple railroads converged and intersected.
Given the quality of your layout, no one should dare challenge the look and feel of your layout. Interestingly, the photos you posted remind me a lot of Grand Crossing, a little further north of Calumet.
If you ever decide to add to your Sweet Home Chicago layout, you might consider a background building such as the one that Walthers offers which features a four story apartment buildings. These structures still litter Chicago, and the railroads still run tracks behind these buildings. Classic Chicago. Here is a link to that structure.
http://www.walthers.com/exec/productinfo/933-3177
Once again, Jon, my compliments to you and you layout. I always enjoy photos of your work.
Rich