Where is the ground in Chicago?

[faraway]

.... To do Chicago properly, you'd really have to incorporate various specific Chicago features, like the elevated streets, the viaducts, the variety of transfer and industrial operations, etc. ....

I agree but you need a lot of space to "do Chicago". Most layouts are smaller ISL and deal in one or the other way with Goose Island some decades ago.
If I could "do Chicago" I would start with the bridges over the Chicago river. They are truly amazing. I watched them many times in operation on my business trips a long time ago. A large areas of the down town area has also an exciting underground. That is the reason why you see relative few small delivery trucks on the streets in that area.