Originally Posted by jib71

I think your plan to stay near the airport is a good one. But if you want to have the option to go out, I'd suggest that you change hotel - stay overnight at Kamata (nearest town to the airport) or near Hamamatsucho (the terminus of the monorail), or Shinagawa (served by the Keikyu line).
- Kamata is an ex-urb of Tokyo with the usual range of izakayas, restaurants, and whatnot.
- Hamamatsucho is not that exciting, but it's a short hop by train or cab to Roppongi or Ginza.
- Shinagawa is also not that exciting. You would need to take trains or cabs to reach Shibuya,

In terms of places to go in Roppongi, Ginza, Shibuya ... I can't think of any places that I'd go to with kids at 10:00pm or later. Family restaurants, perhaps. If you're doing that, you might as well stay in Kamata. (Or might as well eat at the airport). That's just my opinion. YMMV.