Would it be best to store your wedding gown in a breathable or plastic garment bag for the time being?

Actually, the best thing to do if you have the space in your closet is to wrap the dress in a new white cotton sheet. Then every month you need to open the sheet, fluff the dress and wash the sheet to remove any dust particles. This is not a long term solution. If you have already been married and are not planning on having your dress professionally stored then you should invest in a high quality cloth garnment bag to put the dress in. You still should open it every few months ad shake things out and air the dress out for a day to keep it fresh and maintain the shape and structure (if it has any).