I found a very interesting contrast between American, European and Asian attitudes towards names during a trip YYZ-AMS-BOM in February on KLM and Northwest in World Business Clas.

On the first sector with the Dutch KLM crew, I was addressed as "Mister Mendis". On the second sector with a mixed American and Indian NWA crew, I was addressed as "Sean" by the American crewmembers and "Mister Mendis Sir" by the Indian crew.

I'd personally prefer to be called Mr. Mendis until I know someone well enough to call THEM by their first name. I was always taught that when in doubt one should err on the side of formality, but I've noticed that the North American trend seems to be the other way.