When I am travelling for work, I try to scout out the local photographs via flickr or Google Images to see where people are going and what they are getting. The observatory on top of Rockefeller Center jumped out as a great spot to be at sunset. So being in Manhattan last week for work, I made plans to go there. If its going to be a good night for weather/light etc, you should get your tickets online since the line at the box office can push back by an hour or two when you actually get to go up in the building. Also figure there is a line to get to the elevators and you have to go through a picture taking sequence (for images sold back to you once at the top) and a short movie of the building’s history. But once at the top, its amazing.