Back in 2010, we did an 11 night Southern Caribbean cruise on the Magic over Christmas. It was fantastic. It allowed us to thoroughly relax. On a seven night, when you get to day 4, you start thinking that the cruise is now half over.
One memorable item was on the first night when the cruise director was doing the normal spiel, asking how many were repeat cruisers, etc. When he asked about first time cruisers, a few people acknowledged. He 'broke' character and said to them "really, your first cruise is 11 nights? I hope you you like it".
With a longer cruise, you become better acquainted with certain crew and guests. My wife and I spent most evenings in the adult areas. It was generally the same group of folks each night, and we had a great time socializing. A lot of the entertainment crew would come in as well. On the final night, everyone is giving hugs goodbye. Two female crew members came over to me, and thanked me for cruising and gave me a big hug. I did not recall seeing them over the course of the cruise and was confused, as they were generally sincere in their talking with me. A little later, I realized they were friends of Mickey and Minnie. Over such a long cruise, they had remembered us through all our interactions.