KIS - Place a bright red horizontal stripe (with cute graphics, of course) on each and every bin of each and every 700. This way, the FA's know at a glance whether rollerbags will fit "wheel in" on that particular flight and can make the announcements accordingly.

More important, the frequent Customers will quickly learn what the red stripe stands for and can assist by pointing out the "wheel in" trick to other impressionable Customers.

For about $20-$30 worth of vinyl for each plane, you'll get a 90% compliance rate after about 3 months.