I would tend to hang them upside down. This is the model I use http://www.cabelas.com/prod-1/0011358810157a.shtml. Cool air (like from a damp/perspiration/rinsed wader) will fall - out the bottom of the wader. Hanging upside down the wader will stay open and dry. If it is really wet either from a dunking or washing you will obviously hang them upside down. When I have hung waders by the straps I notice that I have to hang them much higher (straps don't like the weight), but more importantly they waders tend to collapse when hung by the straps and are not open for evaporation at all.