After a brief hiatus (football, travel, etc. got in the way), I did 5 streets in north Midtown for a total of a little under 10 miles.
The most distinctive buildings in these blocks are actually two brand new residential towers, One57 and 432 Park. One57 was just completed in fall 2014 and at 75 stories / 1,005 ft. is the 7th tallest building in New York (just behind the New York Times Building and Chrysler Building. It made national news during Hurricane Sandy in 2012, when a crane at the top of the building (still under construction) collapsed and dangled precariously over the neighborhood. It forced the evacuation of all homes/businesses in a multi-block radius for several days while it was removed.
432 Park, still under construction, is now the 2nd tallest building in New York (3rd tallest in the U.S.) at 96 stories / 1,396 ft. When measured by roof height though, it is actually the tallest in New York (the spire on WTC 1 adds a lot). The super-tall, super-thin style of condo building seems to be the next big thing, with three more towers similar to 432 Park in size / shape currently under construction.
Units in these buildings routinely set records for "most expensive apartment in New York", partially due to the fact that they are extravagant modern residences with sweeping views of the city, but also due to demand from wealthy foreign investors. Russian / Chinese / etc. oligarchs looking to move some of their money offshore are buying up new luxury apartments as fast as developers can build them, fueling the boom. Afterward, the unit generally sits empty for most of the year. I've got a call into a lawyer to learn more about squatters' rights.