Two weeks ago, I was in Chicago at the University of Chicago, working. As the Bernard Mitchell Hospital is close to the university, it's not uncommon to hear their helicopter arriving or departing. During the late morning, there was a drone of an aircraft that wasn't a helicopter.
I have no idea what the banner is. East of the University is the 57th street/ Museum of Science and Industry beach along Lake Michigan. I'm sure that's where the airplane was destined. It circled the university 4 times before disappearing. Each time, it was headed from north to south and you couldn't read the banner.
We don't see these things in the suburbs. This seems to be strictly a Chicago and, more importantly, a beach thing in the summer. It's interesting to see what is deemed worthy to be hauled behind an airplane. Occasionally, you'd see sky-writing but that seems to have died out.
One thing we do see in the western suburbs are the blimps.
This is the MetLife blimp and it was out over the beaches near 47th street and Lake Shore Drive. Blimps are usually stored at the DuPage Airport which is straight west of me. I can remember seeing the Goodyear Blimp with its scrolling screen on the underside of the blimp, flying over the house at midnight. Blimps have a distinctive sound so, if you know what you're listening for, you know it's a blimp. They used to give rides when they were in town, too, but I don't know that they do anymore. I haven't heard a blimp fly over the house in a couple of years. Those are impressive since they don't fly all that high. My luck, they will fly over when I'm in the middle of a World of Warcraft raid.
Beverage: English Breakfast tea