I've been meaning to go to this museum ever since just after moved here (and tried once, except I'd misread the website and arrived too early and couldn't wait) but we finally made it there to see their exhibit on socialist realism in Central Asia. The exhibit was small but so wonderful to go to. I love the artwork and the textiles and it was perfect.
Upstairs they had two more exhibits about DC which were really good too, and I'm glad I didn't go at the beginning of our stay since I've learned a lot about the city in the last 6 months. One had a bit about the Albert H. Small Washingtoniana collection and the other had a lot of artwork from Lily Spandorf who worked in DC for years.
There's a suggested donation which I happily paid, but you can easily go in without feeling guilty about not donating. They also have Monday lectures on all kinds of interesting topics (I was trying to go to one on the boundary stones earlier) and other events.