The Brooklyn Museum of Art is lovely. After a major renovation, it looks and feels bright and well ordered. The American collection has especially improved. The main rotunda has been fixed up and it's no longer a hazard. It has an extensive permanent collection, and many traveling collections. A while ago, THE DINNER PARTY came to rest here.
One of the most interesting places in the Museum is the LUCE Center for American Art with a visible storage and study center. There are computers to look up interesting objects. Very cool.
Also, the BMA has the nation's largest collection of Egyptian artifacts. This is a little known fact...take advantage of it!
Definitely stop in. It's inexpensive, convenient to the train line, and close to several delicious restaurants! Right next to the Brooklyn Botanical Garden, too! Make a day of it!
Take the 2, 3 to Eastern Parkway