the terms of the Qantas offer are that it needs to be for flights. I've booked some flights and it triggered the cashback, but an accommodation booking on a different card did not, which is why I looked into it. It would be hit and miss with the gift vouchers.
If you haven't used it already the Flight Centre deal 500/100 might be more suitable
If you haven't used it already the Flight Centre deal 500/100 might be more suitable