Line? For me, I’m going to be selfish and suggest Celebrity. Selfish because I have been primarily Royal but am planning to check out X anyways. And a big part of me selecting X is the coverage by Bill and Cruise Habit.
Where? I vote Caribbean. Done it enough that I know how to enjoy but feel free to spend more time with the group activities.
Activities? Maybe group takeovers of ship specific venues, like the Lawn Club or Sunset Bar. Opportunities to mingle and meet and talk ship. That’s what Cruise Habiteers do, right?
How different? I think skip some of the more traditional group activities like pub/cabin crawl, maybe arrange a session with performers or other staff/crew.
Just my random thoughts as I flatten the curve.
BobJ