All Hyatts I have tried allowed to confirm and upgraded room by paying the standard rate difference. You can book a room for points and then secure your preferred room by paying the differential.
Just to remind everyone of their normal room rates. For 3 March you pay:
Harbour View King: AUD 1,370, Opera View King: AUD 1,470 (+100), Harbour Deluxe: AUD 1,520 (+150) and Opera Deluxe: AUD 2,020 (+650).
They are not charging random amounts for upgrades here, they are charging the standard rate difference.