You've got to think this would be a good topic for someone to do a guide on (either our own editors or pointhacks) about what is the best card for frequent flyers, given CBA is no longer a clear standout. Covering eligibility criteria, e.g. how much, is it per person or per policy, what counts (e.g. must it be one transaction or can it be multiple) ...Westpac doesn't require $500 per single transaction, but its policy provider Allianz does say "have used this card to spend at least A$500 of each traveler's prepaid travel cost", so if you have any family members to travel with you and you'd like to get them all covered, you will have to prepay $500 x number of people.
The fact that you nowadays need to book 11 months out (and hence in this case) would need to keep the card over the 1 year renewal would perhaps provide some additional criteria around value of doing this, some cards have better offers to retain than others.