My little tip as a once frequent visitor to D.C.: If you want to see the view from the top of the Washington Monument but don’t want to spend the time (once at 8:30am for the timed tickets, then return for the actual visit), go instead to the Old Post Office Tower. It’s free and open seven days a week like the Monument, but with almost no wait and almost as tall as the Monument. It’s just off of Pennsylvania Avenue and next to the Federal Triangle Metro station.
The Lincoln Memorial, certainly. Of all the famous downtown monuments and memorials, it’s the one that’s worth its billing. And then some.
Of the less-famous memorials, I’m a big fan of the Korean War Memorial and the FDR Memorial.
The Smithsonian, of course, but pick and choose a few of the increasingly large number of Smithsonian museums; don’t try to do them all.
Things I wouldn’t bother with: the WWII memorial (it practically defines ‘generic memorial with only minimal connection to what it’s supposedly commemorating’), going to the top of the Washington Monument (per John Bredin, do the Old Post Office Tower instead; while it’s not ‘almost’ as tall as the WM - just over half as tall - that doesn’t negate what he said), and the zoo (lots of cities have great zoos).
I agree with this.
Not only is it a shitty, generic memorial, but its presence fucks up the nice clean sight-lines on the mall. The place was much better before they put that monstrosity in.
The Newseum is an excellent destination. Not cheap, but it has things like part of the comm tower of the World Trade Center, an East German guard tower, the taped-open door from the Watergate, Patty Hearsts gun and jacket and other very cool and uniquely historical items.
And remember: Stand to the right on the escalators!
And Don Bolles car!
Whatever else you do, you MUST go to the National Air and Space Museum and touch the Moon Rock.
The entire museum is great, but DO NOT leave Washington without touching the Moon Rock.
</geek>
Been there, done that! 
I stopped at it on my way out and touched it just so I could say that I had.
Adding to the memorials - the Vietnam War Memorial, located just NE of the Lincoln Memorial, is probably worth a stop. You walk along a sidewalk, and the wall starts as just a little wedge of black polished stone, and as the sidewalk dips down a bit and the wall rises up, it gets a little taller and taller, and then names start to be chiseled into it, and you keep walking and the stone rises over your head and the names and new panels of stone just keep going and going. Look down the wall and you’ll see people reflected in its blackness, flowers and notes stuffed into the cracks or laid at the base, people touching names or scanning across line after line of names, looking for someone.
To be fair to the OP: Johnny Rockets is awfully good. But I’d much rather go to Ben’s Chili Bowl if I had the choice.
Blah blah, I agree with most of what’s been said. In particular I echo the recommendation of Air & Space, either on the Mall or the one out in the boonies. If you do go out there it’s $20 to park. The American Indian museum, other than the food court, is no great shakes. The Portrait Gallery is the bee’s knees, but my favorite second-tier Smithsonian museum is the Freer Gallery. The night tour of the monuments is also a crowd-pleaser.
–Cliffy
I don’t know if they still do it, but there used to be a tour twice a day to come down the stairs inside the monument. You go up in the elevator, have a few minutes to check out the view, and then the park ranger leads the group down the stairs. There’s not much to see for the first half of the trip, but then there are stones that were donated to help finance the construction. They’re carved to commemorate the groups that donated them.
Bring good walking shoes, if the weather is nice you can do a lot of the monuments, the Smithsonian, the Holocaust Museum, etc. on foot. They are all on, or around the Mall. You can just wander into a museum, look around and leave for free. There is a nice cafe at the National Galleries, underground between the two. At the Lincoln Memorial, you can also see the spot where Martin Luther King delivered his I have a Dream speech. Ben’s Chili Bowl is a DC institution.
If you want a quick payoff for pure amusement, go into the National Museum and tell the curator, “Hey, I only have 15 minutes until I meet a friend outside. What are the 10 things I absolutely must see right now?” The look on his/her face is priceless (or at least, was when I did this a few years ago - curators HATE it when you seem to take their collection for granted).
Other than that, there are a lot of great suggestions. I think the walk from the Jefferson Memorial around the Basin towards the Lincoln Memorial (via the FDR Memorial) to be a nice quiet walk - but I think I’d go the other way next time, since the FDR Memorial is set up chronologically the other way. The way I did it, the US went from a victorious celebration of defeating the Axis powers to quickly sliding into a horrible depression. It was nice to see that man recover from polio though.
snerk
I agree with this, but also feel this way about the FDR memorial - which is a gigantic politically correct disappointment. The Martin Luther King memorial that is being built looks to be even worse - the statue makes MLK look like Lenin.
I love the Air and Space Museum, and the National Zoo.
Try not to drive on the Beltway during rush hour.
In the city proper, parking is going to be expensive and hard to find, same as in most major cities. The Metro is a good alternative.
It’s going to be hot and humid. I’d worry more about this than about crime. Stay in a hotel with air conditioning (most chain hotels should have it) and be sure to drink enough water if you’re walking around outside all day. Wear lightweight clothing.
If you’re outdoors in the evening, mosquitos may be a problem. The bites won’t give you any particularly nasty diseases AFAIK, but they are still annoying. Get some bug repellent and use it if you might be outdoors at night.
I don’t think I’d heard it called that for probably 15 years.
The original FDR memorial – on the lawn by the National Archives – is worth a look. Simple and exactly what FDR wanted. You can actually spot it using Google Earth street view for 868 Pennsylvania Avenue – a simple granite rectangle with his name on it. This was what FDR wanted, so the newer one is in many ways an insult to his memory.
We visited DC a lot when my daughter was going to college there. I love the National Gallery of Art. Other, less well known places to see are the Folger Shakespeare Library, the Einstein Memorial (sit on his lap!), and the Kreeger Museum
The Spy Museum was hokey but a lot of fun.
As always, my offer is that if you’d like to, we could put on a Dopefest while you’re here. We could meet at some restaurant.
I worked in the Old Post Office for nearly a year and the clock tower is what I’d suggest as well. It’s much more open than the Washington Monument and the building is a short walk from the museums; the back of Natural History is a half-block away. There are a food court and a small stage that almost always has live music at Noon during the week in what was originally the basement. Can’t really recommend the food there unless you want to stop by a Ben & Jerry’s Scoop Shop for dessert.
If you do visit, all that exposed iron work just above the ground floor? 100 years ago, that would have been a glass floor on which the postal supervisors would walk around to observe their staff.
Start your evening review of the monuments at sunset at the Lincoln memorial. Walk around to the back and watch the sun set over Arlington cemetary. (George Washington built Arlington manor, it was later owned by Robert E. Lee via his wife, and was taken over by the Union army as headquarters during the civil war. It still stands, and the grounds are now our primary national cemetary for war veterans.)
Be sure to go through the door at the left of the stairs and view the structure underneath, it’s pretty neat to see the cartoons and graffitti that the builders left under there.
Head down the steps and go left and across Consitution avenue to the statue of Albert Einstein. Get you picture taken sitting on his knee like a little kid.
Come back and walk through the Vietnam Veterans Memorial. I’ve never seen another structure that gives a better perspective of war. You will find yourself walking into a grave-like depression, and slowly being buried in the vast list of names of the Americans who died in that war. As you look forward and realize you are not even near the bottom yet, and there is an equal number of names ahead of you, you may for the first time get a true idea of the vast waste involved in human conflict. As you come out, it may occur to you that those were only the names on one side of the conflict. . .
Come out and head to your right to see the Korean War memorial. The men slogging through the mud are so realistic I was tuly spooked by them.
A good map can be found here: http://www.nps.gov/nama/planyourvisit/upload/NACCmap1-2009.pdf
Also, if you can get a car for a day, head out to Baltimore and see the National Aquarium. It’s wonderful.
“See the Smithsonian” is common advice, but it’s actually ben estimated that spending eight hours a day, five days a week, it woudl take approximately 13 years to see just the standing exhibits, and you’d still miss the extra-special touring shows. So if you want, PM me a bit about where you’re from and what your interests are, I’d be happy to help if I can.
Also, what type of food do you like? If you are a foodie, definitely try now to get a reservation at Komi. http://komirestaurant.com/
GREAT list, TruCelt. One quick note:
Do not,under any circumstances, think “oh, we can’t make it to Baltimore - the local DC aquarium will suffice”. If you find yourself even thinking of going there, just walk a few blocks more and go to the spy museum or something.