Especially on Delta and American, I don't even get brusque professionalism, I get outright rudeness. The longer I've lived in the US, the more I've learned to minimize conversations to flight attendants to "I'll just have water", "thanks" and "have a nice day".
AirTran (now part of Southwest) used to be really nice.
It's always interesting to me how much experiences vary, and how likely it is that our biases also color our perceptions. Almost always when I get on a Delta flight (admittedly I fly them the most), I'll get a friendly hello and what seems like a professional and genuine smile when I get my beverage. My last few experiences on Southwest have been a borderline sneer (if any acknowledgment at all) as I get on the plane, followed by bizarre jokes over the intercom or a round of applause for the plane landing (?).
> My last few experiences on Southwest have been a borderline sneer
I've had the complete opposite experience. I used to frequently fly southwest between Denver and PDX, and the flight crew were chill AF. You can almost guarantee a free drink or two on a southwest flight if you ask nicely -- I can't say the same about any other domestic American airline.
