I've been on the road/air over 12 years now...and fly business/first class whether its using upgrades or paid for pretty much any flights over 2-3 hours...

In North America, I am usually dressed in business casual during the week if I am going straight to client site, or smart casual(jeans,polo shirt, etc...) on the weekends. For overseas to Europe and Asia, I am usually in smart casual, as I will use a travel day to rest up before meeting clients.

I have not experienced much of the attitudes in NA or Europe. But when I travel to Asia, I repeatedly experience it...Whether its during the check-in process or priority boarding at the gate. I guess I don't fit in their image of business/first class passengers. young person dressed casually.