I’m assuming the fact that she was impressed meant that she felt comfortable at both and thinks she could be happy spending four years at either? If you think that both visits were of sufficient length and depth to give her a good sense of what going to school there might be like, then I think she’s going to do well at either.
I am not a music specialist. But I agree with @prezbucky’s point about the location of Belmont. Being not just in Nashville but on Music Row is a HUGE plus for someone who would like to be a singer songwriter. There are people who who want to do work with public policy and will do well no matter where they get their degree from. But those who go to college in Washington, D.C. or state capitals have an edge because they have the whole year to be building professional connections and experiences, not just three months in the summer. I would assume the same is true for people who want to be professional musicians.
Out of curiosity (as I truly do not know the answer to this question), how does the culture at Belmont’s music school compare to the rest of the Belmont campus? I know at other university’s that programs in the arts tend to be more liberal, but I don’t know if that is the case here.