GenY, or is it GenZ now?
Apparently, Virgin Blue are encouraged to refer to passengers as Guests. Personally, when I fly on Virgin as one of their Guests I feel as if I should be a little under some obligation to behave nicely as a guest should. Perhaps this is part of the strategy, to avoid the "customer is always right" issues.
I think SLF is fine in industry circles and most would take it in good humour in public circles.
Having recently flown Qantas and being warmly welcomed and farewelled by the customer service manager, actually referred to as the CSM by other crew, I would be happy to be a passenger or a customer. As I paid for the flight, I am not perfectly comfortable with being referred to as a guest!