I bring everything. I went last year the week of Christmas and had days I was in shorts and days I was in cords and a heavy sweater. Layering is great. I don't do laundry at WDW and so bring something for every day. That HAS to change with the new luggage restrictions, so I will plan on wearing jeans or cords twice, shorts twice and long sleeve shirts once - as I spill. I am also bringing my fleece jacket, my Christmas WDW hat, two sweaters and two sweatshirts.