I heard about this happening at a wedding recently, and had never heard of it before, so I thought I would throw it out there as an idea for people.
One young bride asked the mothers, grandmothers, and great-grandmothers for their wedding dresses, and then displayed them outside the reception, along with their wedding photos. I was pretty impressed that there were enough of these relatives 1) still alive who 2) had kept their wedding dresses accessible and 3) were willing to lend them out! But apparently there were four or fives dresses in all and it made a very nice display. For one woman who had eloped, she gave them her old suitcase and they put that out instead.
I've no idea how much trouble this might have been to set up--finding the dresses, cleaning them, etc.. Perhaps a less ambitious person could do just the wedding photos, though--that would be neat, to have large versions of family wedding photos as decor.