While Stanford and Harvard are both exceptional programs, they each value unique characteristics. Harvard, for instance, is big on leadership. Therefore you should emphasize your leadership abilities - professionally, academically, and personally (hobbies, community service, extracurriculars). Stanford values innovation. So you would want to emphasize your ideas and their impact. It sounds like you can discuss a number of experiences that would fit with either program.
Finally, remember that your professional experience should not be the only topic of your essays. Schools prefer well-rounded students so be sure to draw from all of your experiences as you choose your subject matter.