This may come as a shock, but given how many cards I send out, I don't worry about the gift cards being used. Some people just need to wait until the right time, others have no idea how to use them--despite me explaining!--and if they don't use them, I tell them they can always pass them on. I never nag and remind people because it tends to get taken the wrong way. Once they're out in circulation, I just plain wait... "Out of sight, out of mind." I have too much else to do.