As you go on campus visit for grad school or faculty positions you not only have to decide if this is the university for you, but also whether this is a place where you want to spend a good chunk of your life. You may have done a wide search and be unfamiliar with some of the cities and schools, so what do you look for? How do you pick?
I was debating this issue with one of my senior mentors who suggested a clever approach, develop a ranking system. Define the things that are important to you for your work AND your life, and rank the different aspects of each option. One place may be #1 for work and #8 for life, so maybe you'd rather be somewhere that is only close to the top but has more attributes you like. It's an interesting exercise, especially because it really makes you think about what you want.
This is how I did it for faculty jobs. I came up with 7 criteria for work and 7 criteria for life, so that the scoring would be balanced. I chose things that are important to me personally and that I realized I would like for running a lab:
WORK: good colleagues, resources (cores, internal funding, etc), percent of salary support, students, good administrators, ability to attract good students/postdocs, recognition/ranking
LIFE: large city, proximity to friends and family, good art museum, good theater, good symphony orchestra, weather, distance from New York City
Then I made an Excel spreadsheet and assigned a value from 0-10 to each for a possible total of 140 points. Interestingly, the highest value I got was 106. Being in NYC immediately gives a score of 66, because let's admit it, the weather is not the best. It was clear that there is no perfect place and the final order was not necessarily what I expected. While this is not the only decision-making tool you should have, if you have been going back and forth in your head about some universities and cities, seeing how they rank on all aspects can be eye-opening. Defining your criteria can also remind you to ask specific questions during your interview to properly assess whether the place is a good fit. If you want a primer on which questions to ask and how to ask them there is an old post here. And another here on the all-important, but very loaded "Are you happy here?" and how to deploy it on a job search.
PS: Grad students: I was so confused when I had to pick a school that I literally let it up to fate, so don't feel bad if you don't know what you want. But trying this may help...