The shoes are fine and I agree the purple top is cute, I'm not sure about any of the Pref dress choices. As Low C said, strapless dresses on women with chests are tricky (and you do not want to spend all night "tugging"), and the one with straps looks a little clubby (the description that "your cha cha needs this" on the webstie tips that off as well).
VandalSquirrel responded to another poster with some great, general examples of what would work in almost any Preference setting. Please see this post:
http://www.greekchat.com/gcforums/sh...44&postcount=3 and please note the general lack of cleavage.
And good luck!