There are fake gift boxes out there with weird names of things supposedly in the box. You could get one of those and put the gift card in one of those. You could do a scavenger hunt for the gift card. Hide them in insulated tumblers, a box of file folders, or even a pinata. Anything little you can open can become a gift card holder so long as it is big enough for the card. Take a picture of the family (or the store for the card - the looks you would get would be priceless) and hide it behind the picture (just make sure they find the card).