DTFK (Day Trips For Kids)
Coney Island is definitely a great place to be in the summer. Also spring and fall, but I would not recommend going there when it is cold. There is cotton candy, one or two amusement parks, fun games where you can win prizes, Nathan’s hot dog shop, a beach with the ocean connected to it, and the aquarium* (I went there on a field trip once, I was unlucky it was in February).
*the only one in NYC!