You've heard of "Two Fer's"?
How about 3.
Okay, 4.
Alright, you twisted my arm, 5.
A museum that changes it's main exhibit(see web site)
http://hrm.org/,
a planetarium, a mansion full of Hudson River School art and a view overlooking the mighty Hudson and the Palisades.
Okay, maybe another museum/mansion. But, only maybe.

This Sunday's exhibit is-(See the Video)
https://www.youtube.com/watch?v=GB0hOWjWcUo

Bring money for admission, But, not a lot. And for food. Also, not a lot.
Metro-North Pass in case you have to Bag it.(The Museum is in Yonkers)

Plaza Hotel is at 59th St. & 5th Ave., Manhattan