Ceiling Drywall Direction
Go for the easiest option.  It isn't worth trying to maximize material usage or trying to get a few less seams.

Even 1/2" drywall sheets are heavy.  I'd opt for 4x8 especially if you aren't renting a drywall lift.  Even if you are using a lift you still have to move the sheets around.  A couple more tape seems just isn't a big deal.