When I travel on airlines, I always wear a (dress) sport coat, usually the common blue Blazer. I like the extra pockets it gives me; more space to carry things which is always useful. Some brands are designed for travel, with even more pockets. Also, I have found that this simple garment seems to, how to say it, put me in a different group than many of the other travelers, and get me better service. At least so it seems. (And a Tie helps also.)

So I stuff my coat's pockets with all sort of useful things and don't have to put all that stuff in my already stuffed carry-on.