I've done the hotwire/priceline deal before, but I probably wouldn't chance it for the cruise unless you plan on staying the night before. I can't remember if it allows you to pick a time of day, but I just remember feeling extremely lucky when the times I got were perfect.
They say upon disembarking, you should have a flight at least after 12:30pm. On our cruise we arrived back late and I know our tablemates nearly missed their flight for 11:45am.
On the other hand, about priceline, they've been airing a commercial out here about "the new priceline" which allows you to pick times like other sites. William Shattner is supposedly fired from his spokesman post and they hire Leonard Nimoy as his replacement. That made me laugh.
Orbitz has worked well for us, and we plan on using them again.
goingbacksoon