I been to a lot of museums, mostly regional, and I greatly enjoyed my trips to the Smithsonian in DC the most. A collection of many museums. Fine art, modern art, pop-culture, air/space, science/geology, history, etc. Even three trips was not enough to see everything. I think it probably should be on everyone's "bucket list"... well, at least those who like museums.
Also went to the Spy Museum in DC (not associated with Smithsonian) and enjoyed that as well.
And the National Aquarium in MD, which was also very nice (although I am likely to never step foot in MD again for various reasons).
I can't even remember/list all that I have been to in just Virginia: Fine Arts museum of VA, Hampton Air/Space, Virginia Beach Aquarium, Jamestown, Mt. Vernon, Thoroughgood House, Yorktown, Williamsburg Living museum, VA Modern Art, Naval Museum in, Bacon's Castle, VA wildlife, Natural Bridge, Cape Henry, VA Science museum, Chrysler MOA, Nauticus, VA Holocaust, Monticello, Luray, MacArthur, Mariners', Maymont, Military Aviation, Valentine, more that I am sure I have been to and can't recall right now.
There are a staggering number of museums and historical sites in just Virginia, alone:
https://en.wikipedia.org/wiki/List_of_museums_in_Virginia