Our Captains wear four stripes, and First Officers and Flight Engineers wear three. We don't have second officers, though a few retired captains working in the FE seat refer to themselves that way anyway.
Our mechanics wear two gold bars and a red bar, on a standard flight crew uniform.
When we're enroute, the shirts come off and go on a hangar, and for me it's usually a tee shirt. Then back into the clown suit when we arrive at the destination.
I've seen a few guys who are proud enough of their epaulettes that they buy a second set to wear on their leather uniform jacket. Most of us agree that's a ridiculous thing...but to each his own, I suppose. Most of us don't wear the company issued wings, either. Just a little too much glitz.