Airports: Yes, yes, yes. I wouldn't be caught in an airport without knitting, books, ipods etc. Everyone is usually in their own little space, inner and outer. I annoy no one, no one asks me ridiculous questions, and I don't implode.
Airplanes: It depends. If I am in a middle seat between two over sized gentlemen, then maybe not. If I can make my own little nest by the window seat, probably. I always take it with me and make the best judgement.
Waiting Rooms: Yes. See Airports, above.
So where will I knit? I always have a traveling item and knit while waiting for the littlest school kid to get out of class, while watching kids after school, while riding in the car, with other knitters at coffee shops or Knit Nights, sometimes at the ball park while watching a game.
When I was in my 30's, it didn't bother me to have people make the "My grandmother used to knit" comment. I felt I was doing my part to change the image of knitting from something only little old ladies would do. Now that I am a grandmother, I resent the stereotype, but feel I am adding to it and it falls on deaf ears for me to protest that "No, no. Many many younger people are knitting these days". So it is better for my blood pressure to just avoid the conversations and not knit. I have nothing to sell, I am not an evangelical trying to convert all I see to becoming a knitter. After all, if they don't knit there will be more wool for me.
I do get my knitting time, however, and have completed 2 out of the 6 Who? hats for the granddaughters for Christmas. At this rate I may have them all done before Thanksgiving.