"I would draw a line between 3/4/5 day cruises and the 7 day cruises (on any line). I would say that the shorter trips tend to be party cruises, and the longer ones more geared towards family."
Queen, I can't vouch for ALL 3/4/5 day cruises as being party cruises, but when we took a New Year's cruise on RCCL's Majesty of the Seas, (that was a four day Bahamas cruise), THAT WAS A PARTY! Of course, we expected it and had a great time! For anybody reading this, if you've never done a New Year's cruise, you owe it to yourself to go at least once. The smile on your face will last a loooong time.
Heather, if you and your family plan on eating breakfast on the Lido deck, be sure to look for the omelet station. Many people that cruise on Carnival for the first time tend to miss it the first day or two.