I do. Especially at my base cities. It's been instrumental in making it through the game. Always keep on top of your competition and monitor your routes. ;)
I also check all of the time. And I watch what planes the competition has on order. If I see a lot of wide bodies on order, I know he is planning for long haul routes, or if it is turboprops, then I know the competition is playing for the short haul routes. 8)
in a game like GW2, though, it's a dangerous game. As most orders by good players are done for brokering purposes more than for use.
I'd like to ask, who doesn't do it?