What are the pros and cons of living in the same shared apartment building that house faculty members?
Some pros:
It's an opportunity to network with faculty and spend quality time together, outside of coursework and research. BBQs, coffee, dinners.
We get to know each other more personally, e.g. know each other's families.
I can't think of any cons.
Here is a con.
You might not be as nice or as friendly as you might think. Your presence might be appreciated on occasion, and in smaller doses, but not in large and inescapable doses like being a neighbour.
Maybe you are nice, but maybe you're not. We have no way of knowing. But it's easy to dislike one's neighbors. And if you're looking at this as a networking tool, that means that you're going to look for opportunities to interact more with the faculty. And if at some point you step over a line, or annoy someone in the wrong way (could also be the spouse or the friends of these faculty members), then you become a nuisance. And you might not even be aware that they can hear your TV or your computer playing, and they might not even tell you that, just like I never told my previous neighbors how we heard them fight every night at 1am. Or god forbid, you forgot to mute your recent adult entertainment and their 6 years old child heard it through the paper-thin walls.
It can be perfectly fine if you only interact with these people at work related events, they don't have to bring their spouses and friends there. But you're now encroaching on their private living space. There's no escape from that.
I think it depends on the country, culture, university and also the invidiuals that are involved. I had some professor friend in Vietnam who would go out drinking to the bar with his graduate students. But for me as a professor, I personally prefer to draw a line between my university life and my personal life. I interact with students mainly at university but do not interact with them in my life outside university besides saying "hello" if I encounter them on the street. Being close to students in daily life might be ok or might be seen as inappropriate or a conflict of interest in some countries or universities... I think it need to be evaluated whithin your context (country, university etc.).
I can't think of any cons.
Life is more than just work. Many people want to call it a day and be done with work related stuff. They might not want to talk about work subjects in the evening or on weekends. Sometimes the mind needs some time off a certain topic to be ready to crack problems on Monday morning.
Another issue is that one might not want to spend the free time with work people for personal reasons. Maybe those people simply are not were friendly, maybe those people have (political) opinions you do not want to hear all the time. Maybe some people do not want to socialize with people they are supposed to keep a professional distance?
Naturally at university the lines between private and university life are a bit blurry. Most first-semesters have just moved to a new city and do not know anybody yet. Therefore many will have friends that study the same or work PhD at the same department. But always keep in mind that this does not apply for everybody and not everyone wants to blurr this line
When I was a graduate student, working toward my Ph.D., I wouldn't have wanted such proximity, or assumed that this would have resulted in me being a part of the social circle of any of the professors that I worked with, despite the fact that I got along well with them. It's an uneven footing, so to speak, and some of the joys (and trials) in that time of my life were better shared with friends in similar places (or, if professors, not with those in my department). This was true even though one or two of my professors occasionally went to the bar with some Ph.D. students (and I was a part of this). Universities are often wary of or even prohibit professors from fraternizing (being too close) with their students because a) professors have more power than students, which can set up the potential for exploitation, sexual or otherwise; and b) conversely, it can create a situation where a manipulative student can pressure or even blackmail a professor if something inappropriate has occurred. In addition, it can be awkward. The professor may genuinely like the student, but not necessarily want to bring them into their "friend" circle (or vice versa). It's partly a matter of having appropriate boundaries that both parties are sensitive to. Later, I taught at this same university (a few years post-Ph.D.), and discovered some other issues. A faculty member in another area (same department) offered to give me a lift home following a department-wide professional and social event; he became very sexually aggressive once we reached my place, and his (much) greater power was a possible threat to my continued employment. A student of mine who was my age pursued me romantically, and subtly pursued trying to get a better grade than he deserved. Mixing students and faculty living quarters isn't necessarily a good idea! Living in the same apartment building during the Ph.D. years makes it all too easy to make assumptions that may not be true, and to be emotionally vulnerable, particularly if you're the student, or to feel that your private life has been encroached upon if you're the professor. After I was no longer teaching there, I used to occasionally visit the area where the two professors I was closest to had moved. At that point, I felt free to call them, and we would see each other socially. This was not awkward, and was in many ways an ideal (and respectful) way to be a part of each other's lives.
There are plenty of cons.
And it all depends on the building and where in the building everyone is, and how often you all would see each other.
You should not worry about the social circle because of the age differences.
But one big con is they might try to use you as their butler baby,sitter, or errand boy; and you would not dare say no to them as they, might retaliate. Probably not but you would not take that risk and end up doing too many other tasks.
Your advisor will have you doing plenty of his personal tasks anyway so you do not need other people also doing it.
