The sale applies to Alaska, Caribbean and Europe cruises, as well as Alaska Land & Sea Vacations. More than 700 cruises are on sale in 2016 and 2017.
The upgrade pertains to room location in like-to-like categories—interior to interior, ocean-view to ocean-view, and so forth.
Sample rates, per person, double occupancy, include six-day Caribbean cruises priced at $599 in an interior stateroom and $849 in a balcony accommodation.
Seven-day Alaska cruises start at $749 in an interior room and $1,349 in a balcony room. Alaska Land & Sea Vacations of 10 nights are $1,349 in an interior room and $2,229 in a balcony category.
Eleven-day Scandinavia and Russia fares are $1,899 in an interior room and $2,499 in a balcony accommodation.
The sail runs through Oct. 29 and is available to residents of the US, Canada, Puerto Rico, Mexico and Bermuda.
Information: princess.com/cruisedeals.