Most efficient way from Big Sight to Narita ?

I'm going to be attending an event at Tokyo Big Sight in Odaiba, and immediately heading to Narita airport to catch a flight after that.

I'd like to maximize my time at Big Sight, so I'd like to leave as late as possible without missing my flight.

I have 2 plans and would like to seek your opinions.

1. Kokusai Tenjijo to Shinjuku via Rinkai line (25-35 minutes), then NEX from Shinjuku to Narita (83 minutes). (Total 118 minutes)

or

2. Kokusai Tenjijo to Shinkiba via Rinkai line (4 minutes), then JR Keiyo line to JR Tokyo (10 minutes), then NEX from JR Tokyo to Narita (56 minutes). (Total 70 minutes)

I've done option 1 before. I was wondering if option 2 is much more difficult?

How near are the Rinkai and Keiyo platforms from each other? Do I have a lot of walking involved?

From the station map it looks like at JR Tokyo station, the Keiyo and NEX platforms are on the same level. Is this correct?

Are there large luggage lockers at JR Tokyo station near the NEX platform, or do I have to exit past the ticket gates to get to them?

I've done option 1 before. I was wondering if option 2 is much more difficult?

No, not difficult at all. It just involves some 10 minute walking from the platforms of the Keiyo Line to the platforms of the Narita Express. Escalators are provided.

How near are the Rinkai and Keiyo platforms from each other?

They are just on top of each other. An easy transfer with escalators.

Are there large luggage lockers at JR Tokyo station near the NEX platform, or do I have to exit past the ticket gates to get to them?

There are many coin lockers of all sizes inside the paid-fare area of Tokyo Station. The best place to find them - relatively near the NEX platforms - is in the GranSta area on the B1 floor:
http://www.jreast.co.jp/estation/stations/img/map/hm_1039_3.pdf

Dear Uji

thank you very much for the help!

I am planning to do this on Dec 31, 2012.

Can I check if the rinkai line runs everyday, in both directions?

Because I am planning to use it to get to Big Sight and leave-

Arrival route in the morning
Koenji -(Chuo line)- Tokyo -(Keiyo line) - Shinkiba -(Rinkai Line)- Kokusai Tenjijo

Departure Route in the afternoon
Kokusai Tenjijo -(Rinkai Line)- Shinkiba -(Keiyo line) - Tokyo -(NEX)- Narita Airport

Can I check if the rinkai line runs everyday, in both directions?

Yes, it runs everyday in both directions.

Thank you!

From the station map it looks like at JR Tokyo station, the Keiyo and NEX platforms are on the same level. Is this correct?

No.
Keiyo Underground tracks and Sobu Underground tracks (used by N'EX trains) are on different levels of different annexes in Tokyo Station, and pathways between the two annexes are long.
So, I suppose you cannot do Option 2 within 70 minutes or so.

I am planning to do this on Dec 31, 2012.

Make sure you will reserve your N'EX seat early, because it will be in New Year days.
- http://jreast-shinkansen-reservation.eki-net.com/pc/english/common/men...