If you ever find yourself in NY with time to kill, these are my favorite art experiences in the area. They will require a car and a good amount of driving, but they are beyond worth it IMHO.
Donald M. Kendall Sculpture Gardens at Pepsi Headquarters Free!
http://travel.nytimes.com/2006/09/29/travel/escapes/29trip.htmlhttp://en.wikipedia.org/wiki/Donald_M._Kendall_Sculpture_GardensThe flow between pieces is amazing--truly, the best flow and siting of any museum I have ever been to. Ever. Many, many pieces are dialectical pairs of both the ones before and after. I gushed and shrieked at the quality of planning. K was thoroughly embarrassed. And it's free. Free in an area where even blah museums are $20. And you can hang out on the lawn or have a picnic. Noguchi, Calder, Miró, Giacometti, Segal, Ray, Rodin for starters.
Storm King $20
http://www.stormking.org/http://en.wikipedia.org/wiki/Storm_King_Art_CenterStorm King is Pepsi's gardens eleventy times over. The flow isn't as impressive, but this is one of the few places you can see massive sculptures in the space appropriate to them. Gorgeous mountain drive from NYC with views of the Hudson and Breakneck Ridge. Long trails and beautiful siting. Go, go, go.
Union Church at Pocantico Hills $5
http://www.hudsonvalley.org/content/view/17/47/http://en.wikipedia.org/wiki/Union_Church_of_Pocantico_HillsChagall and Matisse stained glass windows in an old stone church. If you've never seen one of Chagall's windows before, they are soooooo not what you're expecting. Saturated, dark, swirling, messy, driven interpretations of obscure old testament passages. I've been 4 times, and I still see something new. If it were free, I'd go there to read at least once a week.
If you go, drive a half mile up the road to the Stone Barns Center for Food & Agriculture.
http://www.stonebarnscenter.org/ Gorgeous Norman dairy barns built by the Rockefeller Family. Eat lunch at the Blue Hill Cafe ($$) and have a perfect latte made by Alberto, or stay for dinner at Dan Barber's Blue Hill at Stone Barns restaurant. ($$$$) Or just go for a walk. Don't miss it.