We have to fly into Dulles Airport the night before we leave on a morning flight to Kenya. We were thinking of possibly going into Dulles two nights before our Kenya flight so as to have one full day in Washington. We will be staying at an airport hotel and thought we might rent a car for one day and drive into the city. Is that worth it? Are we crazy? I realize we won't be doing any indepth sightseeing, probably just monuments and maybe try to get tickets to visit the Capitol.

What is the traffic like trying to get from the airport into the city in the morning? What about parking in the city? Should we just park near a metro station and ride that in? I know what we want to see, it's the logistics of getting there that are making me think twice if this adventure is even worth the effort. Suggestions are much appreciated.

If you haven't been before it is absolutely worth it, why would you not do this? I would try and stay in a hotel that is close to the Metro, so you do not have to rent a car.

Here is a link that might be useful http://www.wmata.com/getting_around/new_metro/.

We have been to Washington about 25 years ago and we want to stay at the airport because of our morning flight.

I forgot to ask, how long is the bus/metro ride from the airport to the city?

Why not? If you are interested and have the time, it would certainly be easy enough.

I agree with nelsonian: don't bother with a rental car, it will be more likely to complicate your life than to simplify it. In addition to options for getting to and from the airport identified in the link nelsonian gave you, you could take a shared van:
http://www.washfly.com/flyer_ss_about.htm

How long it takes depends on time of day, where - exactly - you want to go in DC, etc. Once you know what you want to do and where you want to go, you can explore these web-sits to see which options suit and how long you'll need for the transportation.

Absolutely worth it. We did that not too many years ago. We had been to Washington before (I had lived there for a short while) so we weren't trying to do the full trip. But we were in town for a baseball game and wanted to look around while we had the opportunity. We saw quite a few things we hadn't been able to get to before. Everything is quite compact there at the mall so easy to add in several museums or monuments in a short time.

We took the bus into Arlington to our hotel. Then again into the city proper.. Use public transportation. You absolutely do not want to drive from the airport to the city in the morning!! Nor try to find and pay for a place to park. Nor drive back again at the end of the day either. Save the car rental for sure.

Public transportation can be enlightening, but it is also easy. I'd plan an hour for the trip each way.

You have time certainly to see the major monuments on the Mall, visit the Smithsonian or National Gallery or Air and Space or Holocaust Museum (note OR not AND) and a photo op in front of the White House.

Should help you sleep on the flights to Kenya!

I would definitely recommend doing it. The tourist attractions are centrally located, and you can see a lot if you're organized.

Use public transportation.

Utilize the Hop-on-Hop off bus to get an overview of the city and monuments and where the big sites are located

Use public transportation into the city. Is there any chance you could fly into or out of Reagan National?

I agree with everyone who is encouraging you not to rent a car for your day.

One option for getting into DC is Metro's 5A Bus which runs from Dulles to L'Enfant Plaza which is close to the National Mall and a Metro Rail station. The fare is $6 cash or Smartrip card and takes about 45 minutes. If your hotel has an airport shuttle this might be a good option for you. Here is the schedule:

http://www.wmata.com/bus/timetables/dc/05a.pdf?nv

When is your trip?

I think that it would be worth the trip. You should probably do a little research before your trip to determine what you would like to see. You could easily see one of the museums and the monuments and still have time for dinner.

>visit the Smithsonian or National Gallery or Air and Space<

Please note, "the Smithsonian" is actually a group of museums that include the Air and Space Museum (one on the National Mall and Udvar Hazy near Dulles), the American History Museum, the Natural History Museum, the National Zoo and several others (unless the referenced quote is referring to the castle).

Use the method obxgirl recommended. Driving in DC is awful, parking is worse.

The only problem with one day in DC is narrowing down what to see! My personal recommendation would be the monuments on the National Mall and the National Museum of American History. Keep in mind that the Mall is deceptively long~almost 2 miles from the Capitol Building to the Lincoln Memorial. Check out www.si.edu for a list of all of the museums and their operating hours. There are several options for hop on, hop off tours; check tripadvisor.com for recommendations.

Keep checking to see when the Silver Metro line to Reston will open, and use your hotel shuttle to get to it. If that doesn't work, go with what obxgirl suggests to get into DC.
Do not even attempt to drive in.

Keep checking to see when the Silver Metro line to Reston will open

Agreed and that is why I asked the question. The ever moving date for opening of the Silver line will have an impact on the 5A bus, modifying it or eliminating it after a couple of months of overlap. The 5A is a pretty popular alternative with both commuters and travelers.

Metro's GM says he will absolutely no kidding have a firm opening date to announce next week, I'd guess before Labor Day.

Stay tuned, OP. It'll get sorted out.