It depends on the airline. I like the Northwest 747s because they have personal air vents and I tend to get warm on the flight, even if I fly business class. I like the upper deck of a 747. I find the 777 can get uncomfortably warm because most new 777s don’t have the personal air vent. After five hours of flying I start to become hot on the 777 and have to battle with the flight attendants to lower the temperature of the plane. Also, if the flight is crowded the personal air vent helps to dissipate gas and other odors coming from other passengers.

I flew the Korean 747 in May and they had no personal air vents, but I was the only passenger on the upper deck.