I agree that it is a need-to-know.

If it is someone meeting me at the airport, then just the flight inbound and the arrival time. But even with family, I don't just forward the conf email because often those have details about price, etc--I don't really want to advertise to my sister, for example, how much I paid for the flight. So I usually cut and paste just flight info, clean it up so it is legible and send only that on.

-ww