I remember the writing the start of How to See the Elephant particularly well, because I went out to lunch to write on purpose, so that I would actually have that hour instead of having it chipped away by work. I went to Pei Wei, and I became so involved in what I was doing that when the waiter came to take my bowl and said, are you a writer? I jumped about three feet and realized I was late getting back. I understand the waiter's suprise. I don't suppose anyone ever started a novel at Pei Wei, because its the opposite of Starbucks in that no one stays there longer than 20 minutes.
But that experience is really the exception for me. I'm not much of a public writer. But I am a travelling writer, and as long as I have my notebook and feel that tight connection with the text, I'll write anywhere.