During the winter, they have a holiday themed train show which has to scale replicas of historic buildings, bridges and skylines (all made of plants!) through which model trains run. Its a personal favorite of Andrea (flowers) and Aaron (trains and buildings/bridges).
A very special place for us both, and our favorite part about living on the Upper East Side!
While we don't love touristy New York stuff, One World Observatory is worth the wait and buying a ticket for. We have each been multiple times. Plus the Fulton Street subway stop is VERY cool and has good shopping.