Not sure if this came up before (I did a search in this thread but didn't see it), but this book called Transit Maps of the World is a great resource to flip through and get some ideas.
New Delhi? 2nd largest city in the world
Middle earth cause who said anything about reality
What about stockholm, looking at the map seems like it would be interesting to say the least
Tokyo, please. Would be fun to also add in a multiple company feature.
I suggest Budapest as an easy map!