Another thought, have everyone sign on the backing of the quilt. Then you can put whatever pictures you want on the front, and use the same colored fabric as your wedding colors.
You can provide multiple colored pigma pens to match your colors.
You can iron on freezer paper to the back of the fabric to stabilize it.
Make the backing 8" - 12" or so bigger than what you want your quilt to be, and turn under the edges of it to keep the signatures where you want them.
If possible, hang it on a wall to make signing it easier for everyone.
Add a pretty border around it out of paper, crepe paper, flowers/vines or something to dress it up.
You could also cut the backing into 1/4's if wall space is too small for the whole piece. Just adjust the size to make it ample for the piecing and quilting process :D
No matter which you decide on, maybe assign a couple of people to this project, give them a guest list so they can check off guests names as they sign. Or one can take pics of everyone signing. If it is close to the door, you can catch guests coming and leaving :wink: