I just felt I should post this, as successful stories calmed me down so much when I was researching flying our two cats over from Finland.
We had the carrier in our livingroom for two months before the flight, and I threw in a blanket and toys soaked in catnip for the flight. The cats didn't mind being in the box, and having each other, weren't nervous at all, mostly curious. I didn't risk taking them to the vet in it (which they hate) or having them in it in the car (they get motion sickness in cars, oddly enough not on the plane) so they wouldn't be scared. I think the novelty of it all made them curious as opposed to scared: this was no trip to the vet or a drive in the car, but something completely new and odd.
We got them out in about 30 mins (EU flights are faster to process with the paperwork), and everything was fine. We had a carrier that was airline-approved, but had no holes in the back, and they pointed that out and said next time have holes drilled in the back as the regulations state to have holes on all four sides of the carrier.
The waiting area is comfy, with couches and a water fountain + vending machine--I'd bring reading for US waits, though, as that takes up to 4 hrs.
It was really smooth sailing, and I suspect I was more nervous throughout the whole thing than the cats (one of which is a bundle of nerves, really).
Oh, and in case either of the two Canada-UK flight people waiting for their dogs there on Aug 26th post here, your dogs were very cute!
(edited to fix an incoherent sentence)
