You have (a) airport buses, (b) express trains, (c) local trains from Narita airport to central Tokyo.

Cost: (a) and (b) costs about 3,000 yen (25 USD), while (c) is about 1,000 yen (8.5 USD), if you take Keisei railway service, plus 190 yen. (You can also take JR -- Japan Railway -- service to Tokyo, Shinagawa.)

These costs are for one way. You need to double them for a round trip.

Time: I would say a little more than 1 hour for (a), with no traffice jams.

http://www.limousinebus.co.jp/

(b) is about 1 hour to Tokyo Station. Frequency is not that high.

http://www.jreast.co.jp/nex/index.htm

(c) is 75 minutes to Nippori or Ueno stations, which are linked to JR East Yamanote loop railway line, which circles the central Tokyo area.

http://www.keisei.co.jp/keisei/tetud...esse/index.htm

Train rides are reliable but I would think it's too much of hassle if you have baggage. Esp. at Shinjuku Station. It's a bit complicated there. I can get lost there quite easily! (I live fairly close to it.)