Just fyi Harvard has a dual degree with NEC that is a BA/MM (Tufts has BA/BM).
For a kid who wants to continue music, and also has academic interests, there is a wide range of options. Honestly, she can probably make many situations work for her. I think it is also helpful to keep in mind the factors all kids think about when applying, since so many situations can work: size, location, academics, extracurriculars, finances, and “vibe.” Keep in mind that some large universities have ways to break the experience down in small units, the honors college or themed dorms, or the house system at Harvard and Yale, for instance.
There are students who attend, say, an Ivy, who continue lessons, practice and performance (on or off campus) and then go on the grad school in music, or go on to work or professional schools like nursing, med or law school. The decision about how deep to go into music can be delayed quite awhile.
A general music major for a BA often doesn’t have a large performance component. This should be researched at each and every school. Performance can be embedded in some classes. Check to see if teachers are available and if your daughter wants to study with them, of course. Check if credit is given for lessons and performance (Harvard added this a few years ago; Princeton has a performance certificate, LAC’s will vary) and if it is funded. Check performance opportunities (yes a city can be good in many ways) A BA in music will include theory and aural skills, composition, ethnomusicology, technology, music history (as will a conservatory). A student can major in music and have access to many professions and grad schools, and it is well respected for the discipline involved.
But it sounds like your daughter most likely would not follow this path- just from the little you have written.If she is not sure, she can apply to all the options and decide in late April!
So,she can do:
BM at a conservatory
BA general music major
double major for a BA (music and something else)
double major in a conservatory (voice and piano)
double degree (5 years) either BA/BM or BA/MM
major in something else entirely for a BA and do music with lessons and performance
Did I leave one out?! Anyway, in terms of your original question (sorry for the tangent), I would not go by the number of majors who graduate, no. I personally would go by the overall quality of the experience, the opportunities in music for both major and non-majors, the location, size and, yes, vibe. Going to concerts can be helpful.
What are your daughter’s other interests and how do they factor into her choices? For those, looking at curriculum, faculty and actual courses helps.
In some ways, if she doesn’t want conservatory, I would consider staying away from schools with conservatories, since opportunities may go to conservatory students. But check that out because there are exceptions.
For a multi-faceted musician who doesn’t want to focus on one type of performance or musical area (voice, piano, songwriting) the choices are very different than someone who has focused on, say, violin, for many years. Berklee would be great if she wanted to do music. If not, there are many schools that would fit the bill. Check out outliers like Bennington and Sarah Lawrence, Vassar as well.