Anonymous wrote:What airline are you on? United tends to have longer lines for bag drop, although you can use curbside (for a fee) which can be quicker.
Pre-check is open until 9 at Dulles (if you have that for the family).
I travel a lot internationally and aim to arrive 2-2 1/4 hours before the flight. I always have plenty of time before boarding starts, even on the big planes where boarding can start an hour before departure.
I would plan to arrive for dinner because that gives you a cushion if you hit unexpected traffic. Not sure I would do Udvar-Hazy as that makes for a long day.
Pretty sure this is British Airways, they have a very consistent 10:45 PM daily departure to London, have been on it a couple of times. Agreed they don't need this much time.