* Natural History Museum.
* USS Intrepid (and Concorde, and Enterprise).
* Walk the old overhead railway (www.thehighline.org).
* There’s a giant M&M’s store near Times Square.
* Grand Central Station.
* Breakfast in Pershing Square Cafe, directly opposite the entrance to Grand Central, under the bridge).
If you’re with kids, don’t try to public transport your way in from the airport. The NY subway and trains aren’t the most obvious to use, so with tired kids, luggage, and commuters it might all end in tears. Taxis to Manhatten are fixed charge at about £40.
Speaking of the subway, use cash in the machines. They throw tantrums and occasionally make multiple charges on UK credit cards, which leads to the bank mistakenly blocking the card. If it asks for a ZIP code when you buy the ticket, put in 99999.