The most recent entry from the University of Virginia’s blog provides a good reminder about which classes colleges care about most when evaluating your transcript:
For now, focus on getting a solid foundation in high school. We consider your core high school subjects to be English, Math, Social Studies, Science, and Foreign Languages. Electives are interesting, but your core foundation is what's most important to us as we're analyzing your transcript.
Most colleges list their recommended high school coursework on the admissions sections of their websites. But you’ll find that just about all of them make the same recommendation—challenge yourself to the extent of your abilities in the core subjects.