As one suggestion, consider the physical aspects of the wellness center. Does it appear well equipped and adequately spacious for the size of the college? Is it architecturally inviting? Is it near the center of campus, or off on a periphery?
Also, look into the specific services available. These may range from traditional psychological counseling to acupuncture.
I agree with @homerdog. One way to gauge student opinions is to look at the student newspaper, which is usually easy to find online. Complaining about student health services, especially mental health, is a popular topic for student newspapers and I doubt anyone writes articles about how happy they are with theirs.
Realistically colleges cannot be expected to provide long term therapy for mental health issues. The student health center deals more with crisis management and then often tries to direct you to an outside therapist. A private therapist may or may not be on your insurance plan – probably not. And then your student has to be able to get to the appointments if they’re in person. The ability to have virtual appointments is a godsend.
The student health center (especially at a smaller college) is usually similar to an urgent care center that handles short term issues (e.g. minor injuries, strep throat, colds and flu, flu or Covid shots or tests, birth control etc). They refer you out for more serious issues, and you have to look to your student’s health insurance for coverage. A larger university will have a more comprehensive health center. For example, my D went to Pomona undergrad and now is in grad school at Penn, and was blown away the first time she went to Penn’s student health center and compared it (size, staffing etc) to what they had at the Claremont colleges.
If wellness is your focus, I agree with @homerdog that you should look for colleges with that type of culture and without a grinding competitive atmosphere.
I agree that the best approach is talking to students and looking at the student newsletter (even better if there is an independent student paper). I would also ask about the training of RAs and other campus leaders to identify students in need of support. This includes individual students and the dorm mates/community. Kids are affected when seeing a friend go through a trying time so their emotional support should be a priority to prevent an unfortunate domino effect.
It’s not just a grinding competitive atmosphere in terms of academics.
Don’t send your kid to a college with a competitive (and brutalizing) frat or sorority culture. How are you going to feel when your daughter feels like a loser for not getting a bid because her hair is “wrong” (whatever that means) or she doesn’t dress according to type? Don’t send your kid to one of the colleges that kids post here have “competitive” ECS that dominate campus life. Yes, if you want to play in the universities orchestra you need to be a strong musician, and that means tryouts. Ditto for theater and ballet. You need to submit writing samples to be on the campus newspaper But a competitive process for the “Business Club”? A competitive process for a club that does volunteer work?
Give me a break. There are SO many ways to undermine a kid. I think the grinding academics (which exist everywhere if a kid makes poor choices-- double majors, insane schedules) combined with a fevered atmosphere around free time- UGH.
For a larger school you can also see if there’s a subreddit that’s active with student posts. On the Penn subreddit I see undergrads periodically freaking out over one bad test score or because they don’t have a sophomore year internship lined up yet. But then other students are pretty good about posting responses that calm the OP down and reassure them it’s okay and that they haven’t fallen hopelessly behind their cohort, and making helpful suggestions.
Sometimes a rigorous and challenging academic program is exactly what a kid needs, and can actually enhance well-being if handled well. I would go so far as to say that the Americans with Disabilities Act and Offices of Disabilities serve to ensure that students with medical or psychiatric issues can be accommodated so that they can function at the level their abilities deserve.
The issue of cooperative versus competitive environment is a different issue. Even then you can “find your people” if other factors fit.
Glad to hear that, as I was wondering - given what’s been shared on this thread - whether academic rigor and mental well-being are mutually exclusive.
No, rigor and mental well-being are not mutually exclusive and that is why I had to comment. In fact, to say they are mutually exclusive can result in actual discrimination or at least preventing a kid from working to their potential.
Boredom causes problems too!
There are plenty of kids with mental health challenges at top schools.
I just happened to look at the OP’s other thread and saw that her daughter wants a challenging environment but a cooperative one.
Yes! That’s the thing, my D wants the intellectual challenge, the academic rigor and energy of a student body that wants the same. But we want to (try to) ensure she can also have a good work/life balance, so searching for that Goldilocks environment, and just hoping it exists. 
Thanks everyone for your feedback. It’s helping me realize I can’t get all the info I want (hard being a control freak), that we’ll have to keep digging in to each school, especially the unofficial accounts of what’s really going on at the schools. I realize those are also subjective but can help round out what’s on the school’s websites and news releases.
Of course even if we have a good sense of what a school is like, it’s still hard to compare with other schools. But I guess that’s what we’re doing anyway with the other factors we’re comparing with regard to academic rigor, etc. Which is I guess why we often look to the school rankings to help make those comparisons.
I will ask about the specific schools on her list and we’ll collect all the info, and she’ll have to with her gut in the end, just like everything else.
Thanks everyone!
Right! I’ve read some descriptions of that type of competitiveness for extracurriculars, and those really raise red flags for me too.
My D wasn’t a fan of competitive entry for ECs either. She took two schools off her list because students said it was impossible for freshmen to get involved in two clubs she was considering. Thankfully not interested in rushing.
With respect to finding a satisfying classroom experience, this list might be helpful: https://www.princetonreview.com/college-rankings?rankings=great-classroom-experience.
Thanks! I found some of their other lists – will be interesting to see which schools cross over:
https://www.princetonreview.com/college-rankings?rankings=great-quality-life
https://www.princetonreview.com/college-rankings?rankings=happy-students
https://www.princetonreview.com/college-rankings?rankings=great-health-services
https://www.princetonreview.com/college-rankings?rankings=most-loved-colleges
I think, at a certain point, it helps to have faith that your kid can make whatever school she chooses, work for her 
Thank you. I really needed to hear that. 
And, honestly, be there for them that first year when things unravel. Because they will. You do not need to physically be there, but be there on the phone listen to them.
Help them figure out if it really sounds is not a good match or if they just need to adjust expectations and priorities.
For my son, we knew at the end of the first semester he needed to try somewhere else. (I knew way before we even moved him in, but he was convinced it was his dream school and was not seeing the things that were going to build up.) It was hard to see him struggle with that experience, but he grew through it and transferred to a school he had not even considered where he has found new passions that he would not have experienced.
My daughter has had some struggles adjusting this first semester, but she knows she has found her place and people. She has advocated for herself and shown herself grace when needed.
And my friend gave me some good advice - have a word or emoji they send as an SOS if things are rapidly deteriorating. Mental health issues are real.
I would give very, very little weight to lists like those Princeton Review ones (and any similar). If any, I would look at the Fiske Guide’s list of those with 5 star Quality of Life scores. It’s quite a short list.
The one thing I thought was slightly helpful was to look at Niche reviews in the aggregate. My son was deciding between 2 lacs, both well known. I noticed one had student satisfaction/happiness ratings well above the other, and I think this was accurate.
Thank you! Yes, I don’t think the Princeton Review or any other lists will be definitive, but I like that they talk to students, and it is reassuring to see some schools that are regularly on the happy lists. I guess they help confirm what I might hear about reputation, or read in other reviews. I do like to read the Niche and Unigo reviews too but just like Yelp take them for what they are. Glad the Niche reviews seemed pretty accurate and helped your son find the happy/satisfying school!
I’m kind of taking in all the feedback and reviews as a whole to get a sense of what the schools vibes might be. I haven’t looked at the Fiske guide in a while, didn’t remember that it had lists so thanks for pointing those out! I’ve always thought that guide had a pretty good handle on the schools that I knew from experience too. Thank you!
This article offers general perspective, especially with respect to the broader aspects of wellness:
Wow, what a great response by Hamilton! Thank you that was very insightful.