The most impressive museums we went to while we were in DC last week were the two Air and Space Museums. It wasn’t a surprise that my husband felt this way – he’s been a subscriber to the Smithsonian’s Air and Space Magazine for years, but I was surprised to feel the same way.
Smithsonian National Air and Space Museum
Location http://airandspace.si.edu/
Address: Washington, DC
Gordie’s Review (3.5 years): “I liked going in the airplanes! Why did the monkey go into space?”
Nicky’s Review (11 months): (signing) “Airplanes!”
Day Pass Cost: Free!
Food Services: McDonalds.
Age Range: All ages.
Stay Length: Expect to spend at least 2 hours, depending on your level of interest you could easily spend all day.
Worth the Trip?: Absolutely
Overall: Even for someone without a major interest in airplanes, there is a lot to wow you right from when you walk in the front doors. Inside the main hall is their Milestones of Flight Exhibit.
They have the Spirt of St. Louis in which Charles Lindbergh made his solo trip across the Atlantic, the Mercury spacecraft in which astronaut John H. Glenn Jr. became the first American to orbit the Earth, the Bell X-1, the first airplane to fly faster than the speed of sound and much, much more. 
They also has a small piece of moon rock that you can actually touch. You can touch the moon!
Seriously, how mind blowing is that?
They also have a real lunar module – it didn’t actually go to the moon, but it could have, it was the back up for the one that did. 
And the actual Wright Flyer (not a reproduction), world’s first successful flight of a powered, heavier-than-air flying machine. 
The exhibits (and there are many!) are well presented too. If you have the time and inclination there is a lot there for you to read and learn, but if you are instead going through it like I was with two small kids, you can still get a lot out of it by just walking through. 
They also have a number of features throughout the museum that really makes it great for kids. 
More than anything Gordie (3.5 years) wanted to go inside the airplanes. There were a number of opportunities to do walkthroughs including the backup Skylab above and airplanes like the one below. 
The exhibits also feature interactive elements that really help keep kids engaged. 
One of the exhibits is even specifically aimed at kids. 
It is filled with hands on elements that help explain How Things Fly. 
We spent hours at National Air and Space Museum. I would highly recommend that anyone in the Washington, DC area at least take a quick look through the Milestones of Flight area.
Steven F. Udvar-Hazy Center – Air and Space Museum
Location http://airandspace.si.edu/
Address: Chantilly, Virginia (roughly 45 minutes outside of Washington, DC)
Day Pass Cost: Free!
Parking Cost: $15 per car
Food Services: McDonalds.
Age Range: 7+
Stay Length: Expect to spend at least 2 hours, depending on your level of interest you could easily spend all day.
Worth the Trip: If you have the time and any interest in airplanes, you’ll be happy you went.
Overall: If you are a big aviation fan, you are also going to want to check out the newer Udvar-Hazy facility. This museum houses the larger items in their collection (as well as many smaller ones).
The two headliners are the SR-71 Blackbird and the Space Shuttle Discovery. 
They are both really cool to see. 
There are tons of other aircraft including a Condorde and an F-14. 
The displays are a lot more similar than at the National Air and Space Museum. It is very much like a whole bunch of cool airplanes have been put in a giant hanger. 
There is a lot less specifically geared towards kids and very little hands on. 
There was one plane (a Cessna) that you could take a turn at using the controls. It doesn’t run all the time as a volunteer has to be there to man the plane. Gordie really enjoyed that. 
We spent a couple of hours at this museum, which was about the limit with our two small kids. My husband easily could have spent all day there, but there just wasn’t enough to keep Gordie engaged for a longer period of time.
If someone in your family is a real airplane fan though, you won’t want to miss the Udvar-Hazy Centre. It’s right near the Dulles airport so it would be a good stop if you have an morning flight into DC or a evening flight leaving DC. If you can only go to one, I’d recommend going to the National Air and Space Museum. It’s easier to access for most people being right along the National Mall and has more to offer for kids.
If you went to both of these museums in two days you could see You could say that in 2 days you can see the first heavier than air, powered plane, a space shuttle and touch the moon