This stuff is great! I think I am just going to cut and paste all the criteria here and ask DD to circle the ones most important to her. Then she can make her own list specific to her based on her customized list. These criteria are many that I wouldn’t have thought of.
Keep the criteria coming!
1 Good Financial Aid (and plenty)
2 Preferably New England so family could reach her easily.
3 Liberal Arts, combining a high level of Science and access to solid Musical instruction.
4 Preferably a pretty campus with trees, where it was not too difficult to get to a city, yet not in one.
5 2-10,000 population
6 No Greek life or party centered schools.
7 Preferably known outside of the USA
8 Lots of clubs/activities outside of class
Some of these, she knew to begin with and some she discovered as we went along. There was always flexibility, as housing and food was/is really important, so it had to be at least acceptable, but the school wasn’t chosen for it.
For me, health and safety, and I think these are both excellent where she ended up.
Different for each kid. For S23:
That resulted in about 20 schools that we visited and narrowed down to the 13 he is applying to.
@relaxmom, there is something freeing about having hard limits and restrictions - so much easier to narrow down college choices from literally thousands across the country to a much more manageable number to which to apply.
D20 applied to three, D23 is applying to four. Once their personal restrictions/needs were accounted for, as well as the restrictions we as parents put down - budget primarily - there were still plenty to choose from (about 20-30 schools for each) but the narrowing process was fairly clear cut. Both had about 10 schools they wanted to visit and from that had 4-5 schools that made a final cut.
For S23 (who basically feels he can adapt to anything)
S22
The norm here and counselor recommendation is to apply to between 10-15, one of them ED. My oldest applied to 18, chasing Ivy admits. Middle one applied to 15 and the youngest is applying to 13. Many of the schools in the list are very selective so they really need to throw a broader net. My middle one had harder criteria - no place north of Boston, no state schools, have to be close to a big city but not urban, extremely smart kids but not intense/competitive vibe, “fun” but not frat/sorority dominated, etc etc.
Since the norm at your school is 10-15 with an ED application assured/assumed, I am sure it felt good to see your children get their lists right around those numbers. 
I wasn’t trying to say that the ‘optimum’ list should stop at 3-5 applications. Neither of my children were looking to go to sub 10% acceptance rate schools (heck they weren’t looking at sub 25% acceptance rate schools) so they didn’t feel the need to have a super expansive number of schools they ultimately applied to.
What I was trying to say (perhaps not clearly) was that having a firm, set budget and some must-haves actually helped narrow the field down and made it easier for my kids to not second guess themselves as much as I thought they might during the admission process. The restrictions I thought could hamper the search actually ended up making it easier for all of us.
It reminded me of a behavioral economics experiment I read about…if consumers were offered a choice of 3-4 jam flavors - they were able to choose one fairly quickly and reported happiness with their choice. If they were offer like 10-12 jam flavors, they really struggled to choose a jam and weren’t nearly as happy as those who had fewer choices available.
Obviously the study results don’t necessarily apply equally - I know friends of my children who applied to many more schools and didn’t have a problem picking from the multitude of excellent choices they ended up with. I was just pleasantly surprised by how happy both of my children seemed to be with the more limited choices they decided to pursue.
Perhaps the big one is cost. Seems that it is either one of the most important ranking / fit criteria in lists posted here, or is not listed at all. Obviously, as the parent, you need to do the financial planning to determine whether cost matters.
I guess for my kids that all of it matters. No doubt cost is a major biggie, but it is one of several.
For most families, cost obviously matters. It should be among the first criteria used to eliminate unsuitable colleges for those families. However, once a college is deemed to be affordable, cost can’t be effectively used to “rank” one’s college list. Should a more suitable college that costs $5k more be “ranked” lower than a less suitable one? Probably not.
The student may ask, is the “better” college worth $_____ more? Especially if the student is looking at professional school later and may be able to use the money for that to reduce debt at the end.
Obviously, the question may be more likely to come up with a difference of $50k than with a difference of $5k.
I ended up looking at cost, area, student body size, and whether or not they let me switch majors. As a student thinking about transferring, now I’m looking at campus size, diversity, culture, and department strength.
S21’s main criteria: Not in FL 
Our criteria: If OOS (FL), then school needs to have more reputable major than that of UF, and the stronger the dept the better.
Other variables:
City preferred
Ease of airport
Diverse student population
Academic excellence of students
Not overly competitive environ
Not too large, not too small
Small classes (at least in major)
Students not going home frequently
Preferably cooler weather than FL
If an honors program is offered, to be accepted in it
May be easier to find in some majors (e.g. classics, philosophy, pure math, astrophysics) than others (e.g. biology, computer science, business, economics).
For S:
Strong business program
Preferred mid-size universities
Urban location preferred
Northeast location
Residential campus
Availability of a wellness dorm was a plus
Preferred no or small amount of Greek Life
For D
LAC
Strength in STEM
Orchestra open to non-music majors
Not a huge core curriculum so she could pursue academic interests outside of major
Residential campus
Perceived fit
Not required to declare a major right away
Not a dominant greek or football culture
Easy to travel to (non-stop flight or driveable)
Good M/F ratio
Good diversity numbers
Most students living on campus
Strong stem, not just engineering and CS
Liberal arts curriculum - either some version of core requirements or strong breadth requirements
Emphasis on team approach to teaching, projects, clinics, undergraduate research, etc
Kiddo was not interested in Southern schools.
#1 Program quality as determined by student. This necessitated a deep dive into
major requirements, classes offered, and very specific “fit” elements. Much of the information is available on university websites, but it is time consuming to collect the details and then compare, and I helped both of my kids with this part. Both of my students also took advantage of virtual and in-person visits, including meetings with professors and attending various classes. One did two summer programs at two different schools which resulted in one school being eliminated from the list. The more effort spent on this element, the smaller the number of applications needed, because all the schools left on the list are winners. Obviously, there needs to be at least one school on the list which is a financial and admission “lock.”
#2 Affordable (Didn’t need to be the cheapest, but needed to be within our max budget number.)
#3 Location. Close to an airport and a real city.
Some kids seem to be very focused on this process and have strong opinions about what they are looking for in a school. My S19 was not in that category, and with him, we just needed to start somewhere. I remember spending an hour or so with him sometime early junior year going through a list of very basic questions - big or small, urban or rural, possible majors, etc. and then, based on that conversation, I think the first Google search we did was something like “small urban colleges with beautiful campuses,” which helped us quickly realize there aren’t too many of those. So then we moved on to small colleges with beautiful campuses and a solid D3 men’s track team. That actually knocked off a bunch of schools that would otherwise have been on the list - to this day, I will read someone’s glowing comments on a school on CC and think “why didn’t we look at that school?”, before remembering the school had no men’s track team. This was before he had any test scores or IB grades, so we ended up with a relatively long list that went onto a spreadsheet. Most of what was on the spreadsheet was just objective data - location, middle 50% for SAT, acceptance rate, deadlines, essays, required recommendations, etc. And then we whittled the list down over time based on additional data and new impressions from him. We did a cross-country round of campus visits the spring of his junior year and he was also able to participate in two large campus fairs with AOs and alumni from many US schools (we live in Tokyo). Those visits and meetings were really helpful to him in trying to figure out what he was looking for. In the end I think his main criteria were something like:
So basically, we ended up where we started, with “small college with beautiful campus and solid D3 track team,” and after that it was mostly his subjective evaluation of fit, but he did find exactly the right place for himself. It was interesting to me that he wasn’t overly interested in dorms or food, although he is usually pretty interested in quality of life issues - I think he figured out those things just weren’t his priority for these four years. He also didn’t have much interest in whether schools had general education requirements. His does and it has been a challenge to complete both his double major requirements and the GE requirements, but I don’t think he would choose differently based on what he’s learned, as some of the GE classes were among his favorites.
Location - eliminated several rural campus schools after visits, ability to easily access a major city for cultural events and possible conservatory level private music instruction. Or being in such major city.
Ability to double major in music performance and social studies field or major/minor in those, and geographic proximity of both colleges/buildings on school campus or in the city - eliminated two or three more schools based on this criteria.
Good school orchestra and ability to audition and join it as a freshman.
Sense of the community or supportive community, that included residential colleges and/or ability to live on campus for 4 years, LGBTQ friendliness, built in support systems for students, including mental health support.
Low(er) student to faculty ratio. Undergraduate focus at the school.
Ability to do interdisciplinary research as an undergrad.
Academic or art merit based scholarships or Honors programs.
Good breakfast places and good food in general. Access to diverse international food - both restaurants and grocery stores.
Good rec center, pool, gym.
1.) Cohort of students. Where would S21 be surrounded by students that would challenge, support and engage during undergrad.
2.) Cost
3.) Environment - housing, parkour, student life…