Boneman- I can't say that I have never encountered a poorly performing Carnival employee. But I can say they are rare. I can't believe what you described about the bar waiters. I have never encountered that. Most of the time we end up running into the same servers over and over again. Like our dinning room server on our Conquest cruise was also in the casino, so he seemed to "claim" me from the other servers. He wasn't the most personable guy but he was a great drink waiter.
I'm surprised at the AC issue you describe. We are normally very cold in our cabin and around the ship, although there have been times where I found it very warm at times in the theater. It clearly was a maintenance issue with you cabin or blocks of cabins. To claim that the AC was leaking out the door was a poor excuse. The door would have had to have been open to leak that much.
We don't do the buffets much except for breakfast but I thought the lines were reasonable when we went by. Personally I never understood why you would go stand in line and serve yourself when you could be eating in the main dinning room and have great servers do the work. But that is a personal choice.
As far as other cruise lines go, I am the opposite of you.. mostly Carnival cruises but we did try an NCL and an RCCL. I didn't care for the NCL cruise mainly because of the service and the poor food quality. We felt that since the dinning room servers may only get you at their table once per cruise that they didn't offer you their best service. The buffet line was always long for us...BUT to be fair it was the NCL Dream which is an older and much smaller ship and our experience probably would have been different on a newer vessel. On RCCL we found the service to be about par with Carnival. And while Dave believes the costs are not that much more, I have found that if you compare apples to apples as far as ship size, time of year and destinations, that RCCL is typically more expensive than Carnival. Yes I am sure that their are some cruises that may be priced at or below a Carnival cruise price, they are not typically during a time when families with school children can cruise.
The truth is that every cruise line is joining to have something you don't like. Most of the time I have found that the cruise line that is the first cruise for a person becomes their "preference" since they end up comparing all future cruise line styles to it. If they have a bad first cruise then they probably don't end up cruising again.
Carnival Cruise Lines:
Fantasy 90, Celebration 95, Victory 05, Conquest 05, Spirit 6/06, Freedom 6/08, Holiday 7/08, Victory 6/09, Valor 9/09, Dream 6/10, Splendor 8/10,Conquest 8/11,Magic 11/11,Triumph 4/12,Spirit 7/12,Freedom 11/12, Triumph 2/13 - The fire cruise
NCL Dream October 2006, RCCL Mariner OTS June 2007