I think one of the first things to decide is what kind of schools she wants to apply to, does she want to go to a conservatory (standalone music school) or does she want to go to a program part of an academic school? I might seem not to make a difference, but they can be very different experiences, in terms of things like liberal arts classes, or among the students. My S went to a conservatory UG, and one of his complaints/regrets was his feeling that far too many of the kids at conservatory are so music focused they don’t care about other things, that they lived in that one narrow little world (and take that fwiw, the complaint of one student at one specific program), but I have heard the same thing from other kids, that they didn’t like the insular nature of a conservatory program and the attitudes of many of the kids there.
After that, it comes down to the teacher, finding a teacher who the student feels is going to be a match. You haven’t mentioned what area your D is in in music, that can make a difference as well, a program that is great for a violin student may not be so great for a person who is let’s say a wind player (violin instruction tends to center around solo work, with ‘orchestral’ instruments it tends to be around orchestral repertoire) a program with a great orchestra may be an important consideration, where it may be less for a violinist (I said may, because nothing is hard and fast, my son chose his grad program in part because they do have a terrific orchestra that was better than his other choice he had narrowed it down to).But the teacher is very, very important. As you noted, that can be very difficult, because how do you know if a teacher is a good fit? As has been talked about a lot on here, teachers are not interchangeable parts the way they are with academic courses to a large extent, it is very individualistic, and a great teacher to one student is a nightmare for another. In terms of even building a list of teachers, that usually comes from kids working with their own teacher, but also comes from talking to other music students and even adult musicians, it also comes to a certain extent from places like this (and there is nothing wrong with putting a question on here like “my D is a X music student who is leaning towards a music school within a university, does anyone have suggestions for teachers we can look into?”.Discussions like “is this teacher any good” are better left to private discussions. Normally kids start with their current teacher, but in your case that is tricky, some teachers are good about understanding if a student wants to look at other schools, others can see that as an insult, plus it is also important that the teacher know what is out there. For example, I would be concerned with the current teacher, if they went to a non auditioned program, do they understand what auditioning is like now? It is much like there are music teachers out there who graduated a while ago and think the music school world hasn’t changed, when the level of playing and competition has ratcheted up.
Once you have ideas there, then it will come down to doing some research. If being within driving range is important, then that would be a filter, or if you decide that only a certain number can be long distance, then that might eliminate some.
Financially, while I generally am of the school you won’t know until you actually audition, get in, and get a package, if finances are tight, unless your family qualifies for significant financial aid, there are programs that are known to be stingy with merit aid (for example, from what I have seen personally, conservatories tend to tie merit aid to financial need, so if your family has a high expected contribution, at places like let’s say Juilliard you are unlikely to get a large merit award to offset it, another program, like Rice, tend to be known for being more generous. ) and that is a consideration in where to apply.
If your D is doing a summer program, if there are other teachers there on her instrument/area, they may be good to talk to about their opinions, or do sample lessons with them. I also would encourage your D to talk to the other students, some of them may be in college already or in the process themselves and kids often share notes on what they are finding, plus it is a great way to find the names of teachers, and to hear what may be the financial situation at various schools.
Once you have a list of programs/teachers, you likely will be able to whittle them down, maybe you hear the teacher is brutal and that won’t work with your D, maybe you hear they don’t do great aid, or maybe D looks and says “I don’t want to go to school in X”.
Once you have a list of potential teachers then I highly recommend, if at all possible, that your D get exposure to as many of them as possible, at least among the top x candidates. Some people do this as part of a road trip to check out the school, others because of the cost of traveling do a sample lesson when they are in for auditions (which can be tricky, teachers are busy, and booking in advance is difficult because you won’t know the time and date of the audition until late in the year before the audition season). Another way is if next summer if a potential highly thought of teacher is at a music festival to try and attend that.
Another way to evaluate teachers is to use resources like you tube and the like, sometimes things like master classes are posted on there, and you can see what the teacher is like.
Also, doing a search on performer bios to see if any working musicians are former students of a teacher is worthwhile, may be tricky (like searching “studied with itzak perlman:” or “student of itzak perlman” for a violin student), but worth the effort.
As I noted before, there is also nothing wrong with asking people on here (privately) when you have an idea on teachers and programs to give their thoughts on it, it shouldn’t be the be all and end all since it is an opinion, but if you start hearing the same thing from different people it may be worth noting it.