My parents recently did a cruise where they paid for an outside with balcony, and were upgraded to a minisuite. They booked at the last minute and got a GTD room, and when they called the day before their cruise to see if they had a cabin assignment, they were told that they were in a minisuite, which was a lot bigger than an outside with balcony. It was pretty cool that it worked out that way because, unbeknownst to the company, it was their 35th wedding anniversary, so it was a very nice present for them. But I would imagine that that's the exception, not the rule.