When I lead essay workshops, I ask students to come up with at least five topics, which they'll narrow down to one. The winning idea should be the story the student is most excited to tell because it honestly reflects his or her best self.
One of the best essays I've seen in recent years was by a young woman who wrote about how being chosen to choreograph a high school musical forced her to assume a leadership role she wasn't sure she was ready for - but of course she was.
The tagline at Westin hotels is that they strive to surprise and delight their guests. This is exactly what a college essay should do.