I teach at a highly ranked(top 25) national university. Our admissions office is looking for strong academics AND extra activities that demonstrate deep involvement in one or more areas of real interest. Trying to be "well-rounded" with superficial involvement in a gazillion clubs and activities is less impressive.
Also, keep in mind that most colleges want a mix of talents each year. If we don't admit any violinists, what happens to the orchestra? We have talent scholarships for musicians, debaters, entrepreneurs, dancers, actors, visual artists etc. Depending on the college, students may not need to be planning to major in music, for example, to benefit in admissions by being a musician.
Our school offers a minor in dance (no major) but has a hand full of talent scholarships for dance. Every year we have accomplished dancers (ballet and other forms) performing in the dance company. They enjoy continuing dance in college before heading to Medical School, graduate school, and various careers.
Many other students don't receive talent scholarships, but may have helped their admission with the talents and interests they demonstrated.
