Echoing the sentiments of many of the other posters, but, anything cloth backed is far more discreet than the crinkly plastic back diapers. As Trevor said, cloth-backed ABU preschools with the additional scent is what you should be looking to get.
I would also argue that if discretion is what you truly want and you are not attached to discretion and a baby-like scent, many medical brands you can buy at drugstores are incredibly discrete and cheap as heck... though, those might not work for you if you're planning on using the diapers. Store bought brands have lousy absorbency.