Keeping the guests warm

Our wedding is outdoors in the evening so one concern is making sure the guests don't get too cold. We'll definitely have a couple heat lamps. Another idea is to offer throws to the ladies who will probably be in sleeveless dresses. Ikea offers the Irma throw for just $2.29. You can't buy it online and only in the store. The only color on the website is a blue but hopefully it comes in different colors. The throws can be tied up in ribbon and offered in a half open treasure chest type of box.