Like Martin Lewis of Money Saving Expert and TV fame, I am very much against giving any shop gift vouchers.
I have been caught out myself when the shop went bust (Focus DIY) so the money was wasted.
I was also caught out when a voucher from Sainsbury had an expiry date which was NOT printed on the card. I went in to buy a CD only to be told at the checkout that it had expired, so another £12 lost, even though Sainsburys had been paid the money.
But on top of all these problems, the recipients may lose them, or not use them, or let them get out of date, and YOU WILL NEVER KNOW that they didn't benefit from your gift, yet the shop will still have had your money.
So I always use a cheque. If they lose it, it doesn't matter as I can send them a new one. And when they use it, you will know from your bank statement. And if they never use it, you will not have lost out and a shop will not have had your money for nothing.