Answering my own question -
ITOKI space is okay for checking emails but gets pretty crowded and noisy once the airport shops open. The nearby Telecube is claustrophobic but offers some sound insulation and privacy for a video conference with clients.
McD is the first place to open for coffee in the morning. (The only place open when I got here before 7).
Coffee
ITOKI area 4F NRT T1
Telecube