Here is the final poster in the series, "Fictionopolis Skylines #3", which includes Wonder Woman's Washington DC and Aquaman's Amnesty Bay.
I had to think a while before figuring out how to represent the invisible plane and aquatelepathy. The Bat-Signal is a lot easier, conceptually.
So now the entire series, once printed out and hung on my wall should look something like this (depending on how I arrange them; what do you think?):