A highlight for me is the Space Shuttle Discovery...one of the three remaining from the Shuttle program (four of you count the Enterprise test vehicle that never flew in space but did fly in aerial testing). Two of course were lost in flight along with their crews, but it was a remarkable achievement and accomplished great things in its long history.
Aviation has successes and failures in its long history and there are some amazing things to learn about in the museum. Of note are the many items that are on display that are not aircraft.
The Langley Aerodrome is front and center in this display. Another plane that caused problems because the museum said it was the first plane to fly (it really did not in two failed test flights) and kept the Wright Brothers from giving the museum the Wright Flyer for a number of years. That legendary plane is now on display at the Museum downtown in DC.
Here you can also see a number of World War I aircraft and even some pre-World War I types. The museum displays even go back to pre-aircraft with early hot air balloon items.
The museum is easy to get to from Richmond with just the typical DC area traffic (though you get to go around most of it) as it is near Dulles International Airport. Admission is free, though parking is $15 (per car, not per person). While there went to see "Sully" in the IMAX Theater and that was pretty remarkable (also pretty cool. There is a McDonalds restaurant there, and prices for that were not out of line for the ones in town.
I was last at this museum four years ago, and enjoyed this visit as much as the last time. In fact I was there at opening yesterday and stayed till the closing announcement (current hours are 10-5). I highly suggest a visit if you are interested in flight, history or just like to spend a day seeing some remarkable and amazing things.