GETTING TO AND FROM THE AIRPORT - If you think the Japanese are smart and efficient when it comes to building airports, please think again. Narita Airport is about 80km from Tokyo, so it is prohibitively expensive to catch a taxi into town - maybe over US$400. You can get buses into the city for a mere 3000 yen (about $30) - most of them go into a terminal called TCAT at very regular intervals. Most hotels will also be served by these buses, but make sure you allow a couple of hours as the traffic can be bad.
Taxi is very expensive from the airport. We took the Narita Express from airport to Tokyo station. From there the taxi fare is may be reasonable. The taxi drivers may speak only Japanese so get a Japanese friend to write down your destination and every one will go out of their way (including the taxi driver to get you there).
The subways and the other trains are SOOOO CONVENIENT! Study that map on your first day and you will maximize your stay. Take note of the Yamanote line so you know how to get back in case you took the wrong train. The bus is also available with cheaper fares but it takes a longer travel time. The scenery though must be better.
I took the train from NRT to Ueno to check out the park and area. It took about 90 minutes (it was the slower train and less expensive). About $10 USD.
Tokyo, the metropolitan is one of the main gate to Japan. There are plenty of international flight connects to other Asia, Europe, Asian Pacific and America Continental big cities.