I believe a good map idea would be in and on an airship. (Think Hindenburg)
is a photograph of what the interior of an old fashioned airship looks like. These were rigid airships. They were not the helium balloons we think of today.
Of course, there are the passenger cabins, control center, and all of that. The airship would have to be flying, and there would need to be some damage done to the ship to make it look scary. A hole in the floor might make for an exciting enviromental danger.
Making the map take place in the air would be very preferable to making a map where airship is grounded.
Airships in world war 1 sometimes had the funcionality of aircrafter carriers. Before strong airplane engines had been invented, they were also used for bombing. Perhaps an escape route could be getting to a plane loaded into the airship, and flying off into the night.
I haven't seen any maps including an airship except for ZPO_Touchdown, but that one doesn't count. If any mappers feel adventurous enough, perhaps this could end up being a map for ZP:S source.