I, too, went the Ziplock route-- folded the dress, put them in the bags, pushed out the air and zipped the bag.
When I bought dresses from the
Disney store, I was told that all of the dresses come in bags and are all squished in a box for shipping, but fluff up as soon as they're taken out. After I heard that, I had no hesitation about packing in Ziplock bags. Also, the dresses ordered from Disney Shopping come packed that way too.
This sure saved a lot of room when you're packing Minnie, Cinderella, Aurora, Belle, and Snow White gowns!!! And it kept all that GLITTER, or umm, Pixie Dust, off our other clothes in the suitcase.
At the parks, I threw a dress in the bottom of the stroller and didn't have to worry about the dress getting wet during one of the thunderstorms. It kept it nice and dry and clean too.
We had no problems with the dresses at all. All that tulle really puffs up!