OP, you may also want to double check to see whether wearing black to Pref is recommended or discouraged at your school- that'll narrow your choices down substantially. That info may be on the Panhellenic website, or you can try calling the Greek Life office.
Hmm...I'll have to check on that. I didn't see much info on the Panhellenic site, so I will try to give the Greek Life office a call.