As I write this, I'm crossing the Atlantic on Royal's Symphony of the Seas. The ship is large enough that despite the number of people, you can find quiet spaces all over the boat.
During the day, the topside is filled with people and music around the pools; personally, I like hanging out by the reggae band. But if you come up in the mornings or evenings, it's a whole different world. You are left with the sea, the clouds and only the sound of the ocean.
I'm a reluctant cruiser; I like the experience, but I get a little claustrophobic around large crowds. However, it seems some thought was put into the design of these ships so someone like me can find quiet spaces to recharge. Anyway, despite the eight thousand people on this ship, right now I'm sitting in a quiet wine bar writing this post. Not exactly sailing, but hey.