Thanks for the explanations.
We have been burning our IHG points accumulated solely from stays as our travel plans for the next 2 years will see few if any IHG stays and we wanted to use points up rather than see them expire.
This booking was the first time our points balance points has been unable to cover the cost for an entire stay.
After a bit of trial and error and an unhelpful call to IHG support my partner worked out a way to avoid paying anything in USD, pay less overall and get double the welcome drinks.
Firstly we decided to book the Indigo Brisbane instead of Voco. A more expensive hotel but quieter from experience.
The trip is for 2 nights and there were points rooms available for both nights at 31k points per night for either a king or a queen room however we only had 32.5k points left to burn.
Paying cash for a King room Friday night was $230 and Saturday was $320.
Points + pay was quoted as 15.5k points plus AU $160 per night charged in USD. Total being 31k points + USD $207 indicating a 3% margin converting AUD to USD over the actual exchange rate before any card surcharges. It was clear IHG was using points for the cheaper night and splitting the points and cost of the more expensive night across the stay.
So we ended up making two bookings Friday night in cash, and a separate booking for the Saturday night only in points. Total came out as 31k points plus AUD $230 saving $90 which will pay for a lovely dinner.
We could have saved a little more by booking queen for both nights, but didn’t want an issue where they might have upgraded one booking and not the other therefore King for nights both seemed sensible and it was better value for the points night.
Google also seems to suggest we likely wont have to move rooms if we call and have the hotel link the bookings. Not an issue if we do need to change rooms, as reception can store bags and we will be out most of Saturday anyway and checking back in means a second round of welcome drinks
Until such time as we have a lot of nights away in the one year where IHG is suitable for most of them, we will be free of loyalty shackles and looking solely at location, amenities and price over earning status with one hotel group.