[gfxgirl]

Wow, I have a very different experience than you. I've noticed vast differences in airlines, how cramped they are, the cleanliness of their planes, the amenities inside the plane, the quality of the food offerings, even the attitude of the staff . And, having experienced all these different airlines, when I'm on a route i've been before I'm apt to pick the airline that gave me the best experience if other things are relatively comparable (price/time)

Even on the same airline, often there are partnerships. For example JAL/American and ANA/United I'm make sure to book the fight run by the Japanese partner not the American partner and the experience will be night and day. The Japanese plane will be clean the USA plane will be less clean. The Japanese staff will be friendly and service oriented. The USA staff will make me feel like I'm a burden on them and they'd rather be doing anything than their job. The food, even though it's airplane food, will be higher quality on the Japanese airline. Etc...