The T&C's clearly state:
InterContinental Ambassador Benefits: Upgrades to a Superior room will be assigned at check-in. A room one category higher than purchased will be assigned to InterContinental Ambassadors.
To me that means if you book the room type below the pres suite you get the pres suite if it's available. If it's not you should get billed the rate for the room category below what you have booked.
To me the word category means a different price not a better view at the same price.
LL