I use Space Bags for my packing. Like the poster above says, they're see-through, so I don't have to worry about strangers handling my "unmentionables". I can also squeeze more stuff into a smaller suitcase, which makes it easier for me to handle (I never bring any suitcase or bag that I can't manage myself). And, as an added benefit, since they're air and water-tight, they make great bags for dirty laundry and those last-minute wet bathing suits!
Beth