We did a photo booth with grandparents and they loved it.
Kids decorated a paper "frame" prior to the event day.
Grandparents came for lunch.
We had a decorated area for them to sit at for the picture.
Pictures were taken both before and after eating (we had a schedule made up).
Students that did not have a grandparent with them could get buddy pictures done so that everyone had a photo taken.
After lunch I took the memory card and had all of the pictures printed and sorted by class (we kept track of numbers on the camera). The next morning teacher distributed the photos and kids attached it to the frame and took them home to give to grandparents.