I'm sorry that happened to you...I know how it sucks, since it happened to my chapter, too. We found out near the end of work week that two other sororities were using the same songs and similar themes as we were, so we had to bust our butts trying to change everything. It was very lousy.
But anyway...what about a Hard Rock Cafe theme? We've done something like that...we've also done Vegas, spring break, and Scooby Doo, which all went over pretty well.