I flew SWA with my dress...
We checked in 24 hours in advance, and I was so anal that i got to the airport so early that we were the first people in line. After the pre-boarders went on, we did. I folded the garment bag in three's, and that way it went easily through the x-ray machine, and when we got on board, it went in the overhead compartment with ease and with room to spare. I traveled with 6 other people, we all had 2 carry-on's so, we put everything in one overhead and surrounded my dress with it, so it was a positive experience, i think that was the only thing with the wedding I stressed about. but it worked out great. then after the wedding, since i had an extra suitcase from all of the wedding stuff, i stuffed the dress in the suitcase and checked it.