Quote Originally Posted by Plastic Paddy
Air and train.
Roll them, every time, with the pleats on the outside of the roll. Then slide the roll into the leg of an old pair of tights/pantyhose! Or you can just roll them and lays the rolls side by side in the bottom of your suitcase. Do not be tempted to put rubber bands around each to keep the roll together, though!

When I travelled around the USA last summer, I took three kilts, a breacan and three Utilikilts (including a solid leather one). The kilts and breacan were rolled, but the Utilikilts were folded lengthways and laid flat on top of the rolled kilts.
No pressing was required in the 17 days I was away from home, but be sure to hang those kilts overnight at every opportunity.