As a midwesterner who has been there once (by myself, trying to get to a wedding) take it from me- it will be like nothing you have ever seen
If you are in the subways, look for piles of garbage on the platforms on the other side of the tracks, you'll see rats the size and shape of basketballs milling about. Call them womp-rats, even though they are a bit smaller than 2 meters.
And don't be surprised (or even react) if someone next to you starts screaming and yelling- it is most likely due to internal stimuli. I watched a woman in a burger king go off like ****** yelling and flailing about being next in line and getting passed up- 50 people didn't even flinch, and I was one of the only ones even watching.
Have a great time, looking forward to the pictures!
edit: the ******* was actually the word f-i-r-e-c-r-a-c-k-e-r - too close for comfort?