Wedding Dress

I would recommend getting a cloth bag, it'll breathe better than the plastic one.

It should definitely be a protective zip up bag (not just a bag with an open bottom).

Whether or not plastic or cloth is better probably depends more on the condition in which is it stored and environment where it is stored. Obviously you want to put your dress away when it is clean and dry and the air is free of excess moisture. If you have a closet that is subject to humid or damp conditions it might be better to keep in plastic. When our basement dehumidifier broke in our house and we didn't repair it right away, some items in our first floor closets developed mold spots. That isn't something I'd want to happen to my wedding dress! But in most climate controlled conditions, I think a cloth bag is a good idea. Definitely keep the plastic one for transport though, as it will better protect the dress from spills and dirt.

My dress was pre-owned and is currently stored in a plastic bag. I have no idea how long it stayed in there prior to it's first owners wedding or how much time passed between her wedding and me getting it, but it was fine when I got it and I've had it in my closet for the past 3 months without issue.

Take it out of the plastic! Did the wedding dress shop not give you a zip cloth bag for it?! It needs to be stored in a cloth garment bag. Plastic can cause it to discolor.

As PPs said, find a cloth garment bag for that gorgeous dress!