Ok, my two cents, Princess is my favorite line. However, most of their ships do not have a sofa in the balcony cabins, only the mini-suites and above. I have not had a balcony cabin on HAL, so not sure if a sofa is included or not. The Royal Princess did have a sofa in the balcony cabin, but I don't think she's doing the Caribbean any longer. RCI and NCL do have sofas in their balcony cabins, but you will run the risk of children, even after the first. Costa also has sofas, but is usually packed with children. So far we've never run into loud music on any cruise line we've sailed on, so I guess we've been lucky.
We normally cruise in late October through mid-December. We have done a few Christmas cruises and even then, there weren't that many children on board Princess. Once we cruised on the Dawn Princess at Christmas for a 7 day and it really didn't have that many children. The other times have been longer itineraries, which normally means less children.
However, just because I like Princess doesn't mean you would. We're in our 50s, too. We started sailing Princess when we were in our 30s. The feeling I get when I board a Princess ship is like I'm going home. I still prefer their smaller ships, the Sea Princess is my favorite. They have 3 ships in that class, the Sea, Sun and Dawn. Now, they're going with the rest of the industry and building larger ships. The Caribbean, Emerald, Ruby, and a couple of others are their largest ships. I still loved being on board the Emerald and Caribbean, but it's not the same as the smaller ships.
Sonny has over 50 cruises on RCI, he's never gone on any other line because he loves RCI. Dave has been on almost every line and I think he prefers RCI, not sure. Lisa, Sandy, and CruiseFanatic have been on almost every line, too. I think Lisa's favorite is NCL, Sandy and CF, not sure. Dwayne and Jim prefer Carnival. So, as you can see, just among the few moderators, there's a vast difference is preference. That's why it's so hard to answer your question:)