Norwegian Cruise Line
Norwegian Cruise Line, referred to as NCL, differentiates itself from its competition in two key ways (and a couple others). NCL pioneered "Freestyle Cruising" a concept that allows guests to have flexible dining times instead of a specific seating. Other cruise lines have copied this, but frankly, NCL does it best (by a lot). With flexible dining times, you make reservations for the time you want to eat, whether it's in the main dining room or a specialty restaurant. Want to see a specific show or see your favorite musician perform? You don't have to decide between dinner and what you want to do. It might seem like a small thing, but with all the activities onboard, you may not want to eat dinner at the same time every night.
If you've seen any advertising for Norwegian, you've seen (or heard) the words Free at Sea. Included perks with Free at Sea are alcoholic drink package, WiFi, Shore Excursion credit, specialty dining, and buy one get one airfare. There is some fine print and limitations, but overall Free at Sea is a good value.
You'll find a wide variety of people onboard NCL ships. You'll be right at home if you're traveling with children as Norwegian has activities and entertainment options for people of all ages, but depending on the itinerary, there can be just as many guests in their late 60's and beyond. If you're traveling alone, Norwegian has studio's for one person on some ships and really do a fantastic job of encouraging solo travelers to do things together.
NCL Vibe on Norwegian Breakaway