I can't believe Top of the Rock isn't more widely known. I was rather surprised when people told me they've never heard of it. The view on top is absolutely breathtaking. You have a 360 degree view of the entire city from three different observation decks. The first two decks have glass paneling but the third deck gives you an unobstructed view of the Big Apple with just a four foot wall to keep you from falling. It was magnificent to be parallel from the Empire State Building at night. The lights glisten in the background creating the most magical backdrop for pictures you could ever imagine.
I do suggest buying a timed entry ticket. They are sold in fifteen minute intervals, I believe. We bought tickets for 8:15-8:30pm for a Friday night (this is just for entry, not the time you spend on the deck itself), but were let in about ten minutes earlier. There were virtually no lines at all. A thirty second wait greeted us at the security line and a five minute wait after that for the elevator. The only problem I had with TOTR was that once you pass security, there's a seemingly mandatory line for pictures. We had a hard time finding a way to pass this line (as the line is the only way to make it to the elevator hallway), but a huge group of people decided to walk past the photo zone and we quickly followed. The elevator ride was about forty seconds long and was quite beautiful. It is made of glass so you can see all the floors you go up. Once you step in, the elevator immediately dims in lighting and a video plays on the roof. Before you know it, you're already on the 86th floor, ready to see NYC!
I could tell you about the views and sights, but highly suggest you see it for yourself. You can spend as much time as you want up there, no one rushes you. Besides the occasional over-enthusiastic tourist that obscures your view and shoves a camera at you for pictures, our trip was perfect. At around 8:45, the third observation deck had about twenty people total. It was quiet and we had the view almost all to ourselves. I cannot begin to tell you how perfect that was.
The line for the elevators back down took about 15 minutes, as everyone was ready to leave, but there were still bustles of people entering the observatories. Do yourself a favor and take a trip to Top of the Rock if you're deciding between Empire State and TOTR. It was absolutely stunning.