Depends on the day. Sometimes I don't mind chatting with a seat-mate or fellow bar patron. Other times I would like to be left to my own thoughts. No different from when I'm not travelling. I just wish people would be a little less obtuse and not assume that just because we are sitting side-by-side on the same plane than I want to converse with them.

Don't get me wrong, I'm exceedingly polite. That doesn't mean I want to discuss the relative merits of the author of the book that I'm reading/trying to read whilst my seat-mate has nothing better to do.

In short - take the hint. Conversation begets conversation. Silence is not an invitation to hear your doctoral thesis.

Cheers,

'toad