Many of the big cities have sightseeing passes and New York does too. There's a New York Pass and a City Pass and with those, you can visit and do and see all you can fit in for a designated number of days, minimum 3. They all have a list of attractions that accept the pass and all are similar. I never find them worth my while as i just can't fit enough into each day to make it break even.
I discovered a pass called the New York Explorer Pass. It can cover 3, 5, 7 or 10 days with different prices for each, of course. The pass is valid for 30 days which is excellent to be able to spread things out even if you're only in New York less than a week. They have a fairly similar list of things to do as the other passes do including the Empire State Building, Most musuems, entrance and transportation to the Statue of Liberty and most of the big museums. There are also discounts at some of the museum gift shops and cafes and a few of the better known stores like Macys. Though they offer various hop on hop off tours, you can only choose one of them and the company they partner with for those is City Sightseeing. Your pass is validated the first time you use it.
The company will send you the pass via courier and it comes with a guide book as well with opening hours and location and websites for more information. Many of the museums and attractions are in the 20 to 25 dollar range so it might not be worth it if those are the only ones you're seeing but if you add a tour or a cruise it then becomes more economical. We took a tv and movie location tour as well as a Circle Line cruise.
New York Explorer Pass