As part of my network of companies, I would suggest you contact Apartment Exchange on Big Bend. They have some great properties for rent near Delmar Loop. I've placed a link below - take a look around. Tell them Bridgette Reynolds from "upstairs" sent you! BridgetteReynolds.cbp1.com
There are lots of great neighborhoods around and near to Wash U. It depends on how close you need to be to the university - are you planning on commuting or are you more interested in walking? Craigslist is a great way to find rentals by neighborhood.