Hmm... It's a shame that my group isn't very Dungeon oriented at the moment, it would be interesting to play through it with my current group...
But what would people want of "The world's Largest City"? Should it be a port city? How modular should it be (as in where you could chuck it in your campaign)? How big should it be (in terms of population)? How should the devision of races be in the city? Should the City be written with different settings in mind? How should it be written (organizational)? Is there a book that does a good job at describing a city, but should be done bigger (i thought Sharn was pretty good, but with an aditional 700 pages of details it would be near perfect).