What is the easiest way to reach downtown Washington DC from Washington Dulles (IAD) airport?

The easiest way is via cab; it is also the most expensive. It is also the only option late at night. It can cost upwards of $80 or more.

The super shuttle is next easiest, and costs a lot less than an cab - but it can take a little bit of time depending on how many people are going, and where you are along that line. It costs less than $30 with tip.

The Metro Flyer Bus to the West Falls Church metro station and the metro train is next easiest, but you need to take your baggage on the metro, which can be challenging, especially if you are arriving during rush hour. This option will cost about $12-14 depending on where in DC you go on metro, and the time of day.

The Metro Bus Route 5A is the cheapest way, at about $2.50 (I think the cost just went up) and it takes you to either Rosslyn (just outside of the city on the Blue or Orange Metrorail Lines) or L'Enfant Plaza (All lines but Red).

It's up to you what constitutes easiest.

mapquest

http://www.mapquest.com/

I'd take a cab. ;o)

If you don't have too much luggage, the subway is very easy to navigate. Cabs run about $50 from the airport to downtown. You can also take a shuttle.

It depends on where in downtown, but the best way is to take the Washington Flyer shuttle (it's about $14 round trip) to the West Falls Church station on the Orange Line. Take the Orange Line towards New Carrollton and it will pass through downtown. Farragut West, McPherson Square, and Metro Center are all near the downtown areas.

If you need to take a bus, make sure you pick up a transfer before you get on the Metro. Cash transfers from rail to bus are 45 cents. It's a bit cheaper if you have a SmarTrip card, and you don't need to worry about transfers.

have you already booked your flight? If not, I would suggest flying into Reagan (DCA) instead of Dulles. I live about 8 miles from Dulles and I still prefer to fly in and out of Reagan. From Reagan you can just hop on the metro (blue line) right at the terminal. Otherwise a cab from Dulles will get rather expensive.

have fun.

If you can afford it, take a cab. It's the fastest and easiest way to go.

If you are renting a car just get on the Dulles Access road RT 267 toward DC, it will merge into RT 66 continue west until it crosses the river and you will be on Constitution Ave by all the tourist spots.