OK, first, what is that picture of?
Second, being a "local" I can give you some tips. You can probably cover 2-3 of the Smithsonian museums in a day. If you only have one day, I'd suggest hitting American History, Natural History, and the Air and Space.
As for the expansion of the Air and Space, they built a completely separate Air and Space branch out by Dulles Airport, which is about 15-20 miles outside of downtown Washington, D.C. It is called the Udvar-Hazy Space Center, and it is MUCH bigger than the one that is downtown. It has a full-sized Space Shuttle in it, a B-2 bomber, and much much more. But it doesn't have some of the classic displays that the old Air and Space is known for, like the Wright Brothers plane and the Spirit of Saint Louis.
Both are great, though. I think Udvar-Hazy is much better for children. And if you make it out to Dulles Airport area to visit it, make sure you let me know... my office is less than 2 miles away from it.
As for the Holocaust museum, I haven't been there in about 10 years, but it is an amazing place. It is very heavy, though, so I would plan something much more lighthearted with the rest of your day when you're done with it. It used to be very difficult to get tickets for it, but I think that's not the case any more since it's been around for a while.
Also, if you come to town, try to arrange to get a Capitol Tour through your congressman's office. Those are typically much better than the tours provided by the Capitol itself.
Supreme Court tours are very neat and don't take much time at all.
White House tours... I mean it's the White House, so it's hard to say "don't do it" but at the same time, it takes a lot of work and time and waiting to get tickets, and the generic tour is very basic. The best thing to do is, if you have any strings to pull, try to get a private tour.... but that can be tough as well.
For the Washington Monument, only go up in it if it is a clear day. Otherwise you'll just wait in a long line and then when you get to the top you can't see anything anyway.
Lincoln and Jefferson Memorials are both great and are "walk up" situations so there's no waiting and are very quick to view if you want, so they should definitely be visited... along with the Vietnam Memorial, the Korean Memorial, and the World War II Memorial, which I have yet to visit so far.