One additional comment:
Boarding First and Business last. On many int'l flights, the attendant from the lounge will walk the business class customers to the jet, and after they are boarded, walk the first class customers to the jet. Actually makes things quite pleasant. The cabins are vacant and tidy when you arrive -- no passengers pushing past, etc.
On SFO-SYD in the cone I have had the departure lounge attendant board me as little as five minutes before pushback. The F/As simply wait for the attendant with the first class passengers, then the agent shuts the door, and away we go. I think this is truly the way to travel. With taxi, there is time for one glass of Champagne before takeoff.