That's one of my kinks too! About a decade ago, my girlfriend at the time sucked me off in an above ground park off Wall Street. We had a bunch of office buildings around us including ours. It was a huge turn on to fuck her mouth where everyone including some of our co-workers could catch us. After one steamy session during lunch we finished up to see a half dozen guys standing at the window across the street holding up signs ranking us all 10s. LOL!
I actually have a balcony here that overlooks the Empire State Building that I've been dying to break in, but sadly haven't had the chance yet.