The Metropolitan Museum of Art, New York.
I was at the art museum in New York over Christmas vacation. I had some time by myself so I was able to do a full dungeon crawl of the whole place. I saw a lot of cool stuff. My favorite was probably Washington crossing the Delaware. Ticket price was a recommended donation of $25.
Of course, not everything in a museum is that great. There a some great works of art as well as a lot of crap, and the natural tendency is to look as everything. That, however, is the wrong strategy because if you send equal amount of time looking at each display, you will end up wasting a lot of time looking at boring an uninteresting items. The trick to getting the most enjoyment out of art is to focus your attention to only the best works and ignoring all the ugly stuff that will distract you.