I'm not "dead set" on the 3 continents cruises, but I have booked a return flight to Rome at the appropriate time for it. It's often less expensive to book round-trip air than it is to book one-way. Also, I've never been to Casablanca.
Although I've never done a "tall ship" cruise, I do have considerable sailing experience. While enjoyable in itself, it's a vastly different experience from a modern cruise ship, and not at all what I go transatlantic for.