World trade center memorial is a must. Central park, times square, empire state building, Brooklyn bridge, ferry to statue of liberty. All are quintessential NYC stops, but of course tough to do in one day. The public library is one of my favorite places. Be sure to go into the rose reading room to see a glorious place (if it's not still under renovation which I think it is). I'd show you around but I'm not home myself. And pick up a pastrami sandwich at Katzs Deli while you reenact the scene from When Harry Met Sally. Have fun...