It takes 1.5 hours from Narita to Shinjuku Station by Narita Express (train), which is a major shopping/tourist area. If you stick to the area nearby the station (which offers a lot of shopping/restaurants), you should be able to manage without getting lost.
Alternatively, you can ride the train to Tokyo station instead. This is the business district and shopping/restaurants are more upscale. This area dies down much earlier than Shinjuku. So if your lay over is in the evening, you may want to consider going to Shinjuku (the ride is 20 minutes longer than going to Tokyo station).
Enjoy!