Prospective biology major with strong interests in political science here. 
Can anyone speak to the following factors in particular?:
- Relative prestige (particularly in bio and polisci)
- Quality of dorms
- Social life - what is it like at these schools? How are they different? Is it focused in the school or out in the surrounding city?
- How does Penn's undergraduate focus compare to the others'?
- How's the food? :P
Thank you in advance for any comments!
First of all, CONGRATS! These are three amazing schools. And i am in a particularly good position, i think, to share a little bit of insight into making a decision between the three as these were my top three choices after having been accepted back in the day!
I will answer your questions but let me begin by saying that I chose Penn because I felt it had the best balance between a rigorous, ivy league education, an incredible urban campus in the heart of one of America’s greatest cities, a social atmosphere that was intense but more collaborative than competitive, and a flexible curriculum that allowed for exploration not only outside of my own major, but outside of the College altogether with opportunities to study in the Law School, Wharton, the Institute of Government, and more. If you have any questions about this, please feel free to ask.
- At the undergrad level they are all extremely prestigious. I will say that Yale has better name recognition than Penn and Columbia among laypeople. And Columbia has a little bit more name recognition than Penn. That being said, Penn has a TON of name recognition and the days of people confusing Penn with Penn State are largely all gone. As for employers and grad schools, they are genuinely considered equals. In political science, Yale and Columbia are better known- but again the difference at the undergraduate level will be negligible. Penn's top notch med school brings a lot of attention to the sciences in general at Penn and so i would say for general prestige, the three would be equal for bio. Though all three are about as prestigious as it gets.
- The dorm options at the three are pretty different. Yale has a residential college system which a lot of students love. I felt it was kind of limiting. I will say that Yale's residential colleges are mostly all beautiful (check out morse and stiles though if you want some evidence that not every one of Yale's dorms is gorgeous..) and they really create the quintessential 'ivy league' experience. They have intramural sports teams associated with the dorms and formal events as well. They have dining halls in most (or maybe all?) of them. It's definitely a great experience if that's what you're looking for. I wanted more control over where i lived, how i lived, and with whom i lived. Columbia has pretty traditional dorms and most people live on campus because braving the NYC housing market is nearly impossible. Penn, on the other hand, has a College House system that allows students to be placed in different communities depending on their living style preferences. Some are suite style dorms like you would find at Yale in Penn's beautiful Quad. Others, like Rodin, Harnwell, and Harrison, are apartment style high rises. Hill College house is being renovated but it has double-rooms that are organized into community 'pods.' And they are nearing the close of construction on Penn's "New College House" (https://news.upenn.edu/news/penn-build-its-first-ever-new-college-house). All of these options, and the many other College Houses at Penn really provide for a unique living experience as your dorm life will differ widely from those of your peers in other College Houses. Students also choose to live off campus (really only within 1 or 2 blocks of campus) in beautiful Victorian era mansions that have been converted into apartments for student living. Penn owns a lot of the land around campus and Penn Police patrol far into west philly as well, giving you the sense that you're still on campus. That being said, you have greater freedom off campus to live in facilities more specifically attuned to your needs. Perhaps you want a big kitchen for your own private use or you would prefer a larger common space to do yoga. Maybe you want a roofdeck or a backyard patio-- those are all options within a block of Penn's campus. I loved the sense of independence I had as someone living off campus at Penn. And I much preferred it to the cramped living quarters at Columbia. Columbia's housing is also integrated with the area around Columbia's campus but because it's new york city, I felt that you lose that sense of campus as you approach dorms that are even a few blocks away. In contrast, because it's only students living around the campus at Penn, you still have the sensation that you're on campus even when you are technically living in your own apartment either alone or with friends. And your financial aid does follow you off campus so you'll be covered if you choose not to live in the College Houses after freshman year.
- Penn's social life is the absolute best. Penn's nickname is the "Social Ivy" and it genuinely lives up to the hype. At Penn, students take their studies just as seriously as they take their social commitments. What i loved about Penn, however, was that being "social" didn't have to mean always partying. It's true that Penn's fraternities and sororities host parties and charity events that are open to all students and that are tons of fun and very stereotypically "college." But students outside of greek life also know how to have a really great time. And because the heart of philly is literally within walking distance of Penn's campus, you can easily take advantage of all that America's fifth largest city has to offer if you want to get away from school for a bit. Penn has the perfect balance of campus life and city fun without either ever detracting from what the other has to offer. There is so much art, culture and food just beyond Penn's gates and so many different student groups, speaker events, and things to do right on campus that the hardest part about being at Penn is choosing which to do first. Philly is the perfect size in which to go to college and Penn's campus and robust campus life do an amazing job of keeping the balance between students looking to go out in the city and those looking to hang around on a friday or saturday. At Columbia, I felt like the campus was too small and cramped and it led a lot of students to socialize away from heart of the school. It also felt like Columbia lacked traditional school spirit. The administration at Columbia is also extremely intense with its students. They give them a hard time when they try to plan events like their spring concert, Bacchanal, and make it impossible to congregate in large groups because of the very limited venues in which they can host on campus events. Additionally, because they have so little green space, the lawns at Columbia are often covered in tarp and inaccessible to the students. But NYC makes for a really good time for Columbia students in a way that their on campus life does not. I also felt as though there was a culture of competitive complaining at Columbia that is hard to explain until you spend some time there. It kind of exists everywhere but I found it to be the most glaring at Columbia. In contrast, Yale has an extremely robust on campus life but New Haven is lacking. It is significantly smaller than either NYC or Philly and it lacks a lot of the opportunities and charm that exist in those larger cities. Most Yalies, however, very happily enjoy their time on campus. In terms of balance however, Penn has the best mix of campus-city life, in my opinion.
- Penn is EXTREMELY undergraduate focused. Yale and Penn have a nearly equal number of undergraduate and graduate students while Columbia undergrads are greatly outnumbered by graduate students. And undergraduates at Penn occupy both the physical and metaphorical center of campus life. The One University Policy also allows undergrads to take classes in the other undergraduate schools as well as the graduate and professional schools on campus. This means that professors, even those employed by the graduate division of the School of Arts and Sciences and the Law School know that they might be teaching undergrads at some point. It has also encouraged professors throughout the university to incorporate undergraduates into their research efforts. All three schools have a 6:1 student to faculty ratio and they each spend about the same amount per undergraduate pupil on things like financial aid and student activities. At Columbia, however, I did feel like there were times at which undergraduates took a back seat to graduate students. For example, Columbia undergrads can't access the internet in the Law School Library and it continues to be a small point of contention. It's little slights like not making a library completely accessible that can make the undergrads at Columbia feel a little less loved by the university than their grad school peers. Columbia's famed core is also extremely interesting as an idea but in practice some students find it wanting. For example, the University has trouble attracting the best faculty members to teach sections of the Core and consequently your friend might have Judith Butler as an instructor for their core section and you might have a graduate student who is writing about one of the books on the syllabus for their dissertation as your instructor. All that being said, all three will provide you with a highly undergraduate focused education that will serve you well.
- I didn't like the food but I think philly and the foodtrucks that pepper Penn's campus MORE than make up for it. And like c'mon, cheesesteaks are an actual gift from the heavens above. Although, apparently some people love the food at penn: http://www.collegerank.net/best-college-dining-halls/ So take that for what you will...
In general, i want to emphasize that you cannot go wrong in choosing between these three. I chose Penn over Yale and Columbia (as well as a few other ivies) because I believed it was the absolute best fit for me. You need to be happy for four years and you need to position yourself well for the future. The best thing you can do is decide what matters most to you as a student and find the school that has those qualities. If you have any questions about Penn or about choosing Penn over Yale and Columbia, please feel free to let me know. It was the best decision I’ve ever made 
Why don’t you take a long term view and research the outcomes for your desired majors at each school?
^ That’s a great point. Definitely check out Penn’s Career Services Senior Surveys (http://www.vpul.upenn.edu/careerservices/reports.php). Penn students from all four undergraduate schools go on to highly successful careers. Be sure to look at the specific career destinations of grads from your intended majors and from several years as multiple years of data will help give you a fuller picture where students go. And be sure to compare this data to that made available by other schools.
DD chose Penn over Columbia. She did not apply to Yale after a uniquely, almost comically bad campus visit to New Haven.
The key differentiators for her:
- She thought she would enjoy her 4 years more at Penn. Social life is more centered around the campus, where at Columbia it is more centered around the city.
- She preferred the more flexible Penn curriculum to Columbia's core curriculum. That has allowed her to add two minors to her major, which she could not do at Columbia an still graduate in 4 years.
- She did liked Penn's much larger main campus (about 10x I think). That means that the athletic facilities are much better. For example, Columbia's swimming pool is small and literally underground, and Columbia's football field is not on the main campus at all.
Penn has all kinds of foods around the campus and in the nearby city neighborhoods (you can easily get there by bus, train, taxis/uber - not too expensive).