You know, I don't recall reading much about other cosplayers packing costumes for travel. I didn't think about this until I was packing the car for Comic-Con, so I'm only showing my already packed bags, but in the future I'll show how the costumes are folded and packed.
The Darth Malgus duffel bag is new. I like looking through the bags at rummage sales, and I recently found a couple of duffel bags in a different sizes. Perfect for storing armor, or unusually shaped pieces. All of the Malgus armor, including boots, headgear, and makeup kit (!) fit into one big duffel bag. That's an improvement over the TWO bags I had to use previously. The only thing that didn't fit into the new bag was the light saber. I still haven't found a good container for something that long. To keep it somewhat safe, I wrap it in a towel. I'll probably need to make a travel case.
The Headless Horseman costume is divided into two bags. I use a garment bag for the coat, pants, vest, and miscellaneous clothing. Since they aren't armored, those pieces are kept relatively wrinkle free on hangers in the garment bag. All of the other weapons, holsters, body suit (with shoulder extensions), boots, and the neck accessory (hat) all pack into a smaller duffel bag. Unfortunately, the ax doesn't fit into either bag, so it goes separately with the ax head protected by a pillow case.
Oh, and by the way, COMIC-CON!