Ad how did the other flooring hold up?
Never want to install plywood perallel to joists...eekI installed the plywood subfloor parallel to the joists (for a shed) and it sagged between the joists as I walked on it. Not good. You see, this plywood had 3 plies going the long way and 2 plies going the short way and that made all the difference in terms of rigidity of the plywood sheets.
and guarantees over time? construction wise itis always better to do it perpendicular to the joiststhe only problem with running parallel with the joists is if there are any dips or humps between the joists the flooring will follow. perpendicular to the joists it would span them better and wouldn't be as noticeable. but if your floor is nice and flat it shouldn't make any difference.