What I find works best when you have a bunch of costumes is to fold them as neatly as possible (sometimes putting a sheet of tissue paper inside the fold helps to keep the wrinkles out), and put them in a space bag. You would be surprised how many of them can fit in a medium-large space bag, and they do not weigh a lot. I take them out and poof them up when we get to the resort. They do not look perfect, but they are good enough for pictures at the character meals, and in the park (only if she wants to keep it on). I used to take the matching crowns, wands, and shoes, but now I take a pretty pair of white and pastel light up sandals for all the Princess and Tink gowns, Minnie shoes, and only two crowns. I pack these in bubble wrap in my carryon. Hey, I need to enjoy her costume time while she'll still wear them!