Hallo Lochman, willkommen in Forum!
I flew LHR-ORD and IAD-AMS in December/January (for Times Square 2000 by the way) with UA 777 and both flight were good. You can't be sure that you get PTV's in economy, they worked only on my return flight.
On the PTV's they just show some movies or clips (no games and I also had no airshow, what a pity).
The food was allright, like BA food I would say. The seats are pretty comfortable BUT TRY TO AVOID SITTING IN SEAT "E" 'cause that will mean double "excuse me" and that really pisses you off!! Try to get a window or aisle seat.
Well, some of the flight attendants were very nice and funny (the young ones) and some were pretty rude (the older ones).
Anyway, you'll have a great trip, the 777 is a very nice aircraft to fly with. Try to take some pictures and post them here! Also don't forget a trip report...
the WorldTraveller (from DUS)