Boston's Logan International Airport has free wifi, but for that one needs to either take a survey or watch an sponsor advertisement. Well, 30 seconds, so I watched the ad. Chicago, O'Hare, there were hajjar SSIDs. In Beijing, one needs to get a user id and passcode from the airport lobby office.
Whatever it is, no comparison to Vancouver International Airport! No ads, no username, no password. Just connect, and browse. :)