For the empire state building, personally I don't think it's worth. If you haven't been there, forget about it.

It costs you $20 for the lifts to 80 floor. Again pass through the airport security check. Force you to take digital picture with empire state building at the background, of course selling you hard to buy it. If you want to go to 100+ floor, you need to pay another 20...

I would love to spend more time in Natural History Museum at Central Park. That's so much to see and it's huge.