Never known an aircraft to have 3 isles, but I would certainly favor it over center seats. Personally, I don't know how anyone can stand a center seat on a long flight unless you are next to someone that you know and can lean on to rest your head.

I know it sounds crazy, but I suggested to Boeing that they make their larger aircraft with two floors and place the cargo in the center of the plane. That way, each floor would be divided into two sections of either rows of 3 or 4.

seat seat isle seat | cargo | seat isle seat seat or

seat seat isle seat seat | cargo | seat seat isle seat seat

I observed that on wide bodies, there is a lot of space in the center of the plane that gets wasted because the ceiling is much taller in the center.

At least this would insure that nobody would have to have a center seat. One reason I like the 767 is that there is only one center seat per row and the odds of being stranded in the center seat are much less. I begged Delta not to stay with the 767 on long flights, but they will be getting some 777's too.