Wow, lots of great replies...and this thread even made it to the front page of FT

Who knew this was such an intriguing topic??

I think I'm going to wear some Adidas athletic pants and a comfortable (yet presentable) t-shirt for the entire trip and that way I'll be set for sleeping but I won't have to change until I get to the Arrivals lounge in HKG at which point I'll change into my "regular" clothes for the day