Geometry, of course!
We decided to go to Empire State Building observatory during the night, and it was the right thing to do, the city lights are just breath-taking! You can enjoy the full power of human civilisation in just one spot!
Now, I consider sunset to be even more exciting time to go, especially if you wait after it will get completely dark and lights start to appear slowly - as far as my imagination is right about it (just be prepared for a very long waiting line or simply pay extra fee for VIP pass through).
After listening to interesting audio tour with a lot of nice, but sometimes a bit fake/artificial impressions, like "I just looove this city, as a young boy I loooved to walk on Brooklyn Bridge, etc..." (similar style of making audio tour you can experience at Boston's Prudential Tower aka Skywalk Observatory), I noticed that, there are two interesting aspects you should take into account when developing... NY-like city generation algorithm.
Can you spot so called Flatiron Building on the photo ? This was the most inspiring example to me. Generally, I divided buildings into two categories: first contains bulidngs that shape fits into street design, the second category contains the rest (buildings that for some reasons, use inefficient amount of space - as Ken noticed). And what is apparent in New York, there are many buildings that efficiently and as many that are inefficiently occuping space between streets (and in general, there are too many of them ;)). Flatiron has sharp angle and is efficient, while there are some with angle more than 90 deg. (where Broadway cross Avenues at more than 90 deg. angle, just note the small building on the bottom-right), some are just square-shaped even if there is so much room around them. I was so excited about this discovery that I almost forgot to enjoy the view in ehm.. humanistic kind of way :)
