We, a couple in our 50s, have sailed many times with Blount (formerly ACCL - American Canadian Caribbean Line) and absolutely love it. Here's the deal: The cabins are small, efficient, clean and comfortable. Public space is abundant: top and aft outdoor decks, a large lounge and dining room. The crew is very friendly and accessible creating a relaxed family atmosphere. They are caring and real - no put-ons. The food is healthy and delicious with choices at every meal. Everything is homemade and tastes it. Even all the baking is done onboard which is tough on the waistline. Beer and wine is served with lunch and dinner if desired and the BYOB policy is great. The ship supplies mixers, condiments and soft drinks.
Most of the cruisers are in their 60s, 70s and 80s but surprisingly spry and adventurous. Many are experienced boaters/yachters who are happy to let someone else take the helm for a change. There are bikes and kayaks available on some itineraries and, at least in the Caribbean, almost daily opportunities for swimming and snorkeling.
Because of the unique design of the ships, they have access to small isolated ports. The other ships in port are usually private yachts. Also, when visiting a port we feel we are not "invading" the towns since there are only 50-80 of us onboard. We don't change the ports - the ports change us. We get to visit incognito or, if the town is really small, we are treated as appreciated visitors. It is close to private charter cruising - more like independent travel than a tour or a big cruise ship. That being said, it is so nice to have your cabin and the welcoming ship and crew to return to and not have to pack/unpack or find a restaurant or negotiate a busy hotel/resort/cruise crowd.
We have been in every category of cabin on the ship. If you are sensitive to engine noise be sure to book on the 50s deck (lounge deck). Otherwise the less expensive cabins are fine. We find that after a day or two getting used to the new surroundings we are fine anywhere. There are twin beds in most cabins, a small but perfectly useful head with a separate shower. The cabins are serviced daily and you can customize the amount of service you require, ie. towel changes, etc. Each cabin has personal control or temperature.