Within the first few days of playing FF14, I've discovered an unsung aspect of the leveling process.
By having all the classes progress independently but still benefit one another through cross class skills and unlocking advanced classes, I am able to have one class on which I play with my wife and progress the story while also having other classes to play when she's busy (or vice versa). I still feel as if I am progressing my main character, preparing for level 50, but without ending up on different steps in questing. Normally, I would have to have one character for leveling with her and one character I would play when she isn't around, which would end up frustrating us both. I've been able to avoid this problem in some more horizontal progression games but those are pretty rare.
Bravo FF14.