We just came back from a wonderful trip to New York. We were a bit worried about entertaining the kids while we were there but we ended up finding some great family things to do. So I thought I would share them with you:-

The Central Park Zoo - they have a special Tisch Children's Zoo which has a petting zoo
Childrens Museum of Manhattan - they have many events going on for kids and special arts and crafts
FAO Schwartz - a toy store similar to Hamleys
New York City Photoshoot - we did a family photoshoot around New York's famous landmarks with a professional photographer. The pictures were lovely and for once everyone in the family was in them. Their website is New York City Photo Shoot tours are the most memorable way to experience New York

So don't worry about traveling to New York with kids there is plenty for them to do!