If you love Art, this is the place. All the masters are here and entrance is free. The Museums mostly close at 5 so trying to grab a quick visit on business can be tough. If you have to choose, go here.
The Mall has beautiful statues and museums that tell the history of the United States. It continues. to grow with additions recently Native American and Black American museums.
This experience only has a few reviews, but you can read what other travellers have to say about the operator.