We felt very fortunate — it was completely unexpected, and very welcome, although we both travel fairly light and didn't actually need all that extra space.

I had to buy a new suitcase last year (my previous suitcase was something I bought in 2005, and the wheels had deteriorated completely), and I noticed this time around that it was almost impossible to buy a suitcase that was a) soft (rather than made of hard plastic) and b) on two rather than four wheels. I was insistent on both counts, because hard plastic is inflexible and there's less space (and more chance of the zip exploding if the bag is overpacked), and for exactly the reason I outlined in my post when it comes to the number of wheels. Four-wheelers need to be held to one side of the body and pushed along, but two-wheelers are dragged behind. The motion required to push along a four-wheeler suitcase is impossible if the ground is at a steep incline. Inexplicably, they seem to be a much more popular option (if my experience observing my fellow passengers at airports is representative). I assume their owners go everywhere in taxis.