In some fo our cruises the balconies have sold out months before the sailing date.
We did get a an up-grade once from an ocean=view to a balcony.
Since then we allways book one to make sure we get it.
Carnival Liberty New Year's Eve 2007
Liberty of the Seas 5/2008+11/2009
Allure 1/16/ 2011
Booked Vision of the Seas . 2/14/2015
Booked Allure of the Seas... 2/21/16 *Last Gang Cruise*