Cheaper 10 day? JR East Pass or Suica

Which is cheaper for 10 days? JR East Pass or N'ex/Suica?

1). I am staying mainly in Tokyo area for 7 days with
2). 1 Half day excursion to Matsumoto Castle
3) 1 Half day at Tokyo Game Show, Makuhari Messe
4). 1 Full day at Tokyo Disneyland
5). 2 days in Nikko

Which is cheaper to get around in Tokyo with, since the JR East Pass 10 day is $300... is it cheaper to get a Suica card and just pay-as-I-go? I am asking about the Suica card cause I don't know how much I am going to be using the trains/subways in Tokyo and I don't know the fares out there.

Can you advice?

1). I am staying mainly in Tokyo area for 7 days with

The average tourist probably spends about 200 to 700 yen per day on JR trains in central Tokyo.

2). 1 Half day excursion to Matsumoto Castle

Half day? The trip there and back already takes half a day!

Round trip by JR train: 6 hours, 14,000 yen
Round trip by bus: 6.5 hours, 6,000 yen

3) 1 Half day at Tokyo Game Show, Makuhari Messe

Around 1000 yen for the round trip

4). 1 Full day at Tokyo Disneyland

Around 400 yen for the round trip.

5). 2 days in Nikko

From 2640 yen by Nikko Railways:
http://www.japan-guide.com/e/e3805.html

Now you can make the calculations.

Wow, so it is much cheaper just to get the N'ex/Suica instead. Wow, I probably will save about $100.

Oh, about Matsumoto I am going there out of Shinjuku at 6am, arriving at 9, then coming back at 4pm. Sort of a half day. Just staying 3 hours in Matsumoto.

Thank you so much for the help.