I just got hired on and it was a two-day affair. If they can, they fly you in that morning, otherwise they fly you in the night before and put you in a hotel at their cost (which most places don't do). You then fly back that afternoon/evening.
For the second round of interviews, it was the same thing. They're now combining the second interview with orientation (provided you make it through the interview).
It makes for two long days, but you aren't out of pocket except for the two days you take off of work. Most other airlines will fly you in the day before, so you're still looking at a couple of days off. But you have to pay for your own hotel. So the CoEx way, even though it appears convoluted, actually works in your favor.