what train pass should I purchase in Tokyo?

Hi,
I will be extending my stay in Ginza Capital Hotel for 4 extra nights (5 days) on my own after completion of my company guided tour of 3 nights covering Hakone,Asakusa and Tokyo central area like Ginza
I would like to visit Shinjuku,Shibuya and surroundings like Yokohama.

Should I purchase a two-day special pass for 980 Yen at the airport (for my first two days) a JR Kanto pass for the next 3 days for 8000 Yen. Does the Kanto pass entitle me to travel from Tokyo Station to Narita airport in my 5th day?
Is there any other alternative because train fare from Tokyo to Narita airport is 2940 Yen by Narita Express.

Based on the location of your hotel, the two day Metro pass would pay off for getting to Shibuya/Shinjuku, and take more than 6 individual subway rides over the two days, it will start to pay off.

If you are only going to use a JR Kanto Area Pass to get to Yokohama and Narita Airport, it will not be good value. Yurakucho (the nearest JR stop to your hotel) to Yokohama is just 900 Yen roundtrip.

You can check fares here:

http://www.hyperdia.com

Get the round trip Suica/NEX package. You'll get a big discount on the NEX fare. Use the Suica card fro transportation within Tokyo. Metro pass only covers Metro subways. It's not a very convenient tool. The Suica covers it all.
http://www.jreast.co.jp/e/suica-nex/index.html

Which rail pass depends on, of course, the location of your hotel and where you plan to go. At this forum, it is advised Day Passes in Tokyo are either inconvenient or too expensive for most travellers.
http://www.japan-guide.com/e/e2017.html

If typical one ride costs 200yen and average travellers ride a train 5 times a day, Metro pass would pays off. In this case, you need to decide not to take convenient JR Yamanote line.
This is why it is advised so.

http://www.tokyometro.jp/en/ticket/value/travel/index.html#anc03