Not sure why you think I'm assuming anything. This is my opinion. I did not explain why, but I will now.
I think that cost of living is more attactive than perceived "fun factor" for several reasons. First, cost of living indexes are pretty standard and are, in a way, more "true" than something totally subjective, like how fun a city is. For example, if you are choosing between Oklahoma City and Chicago, it is pretty much fact that it is cheaper to live in Oklahoma. Your dollar will go farther. You will be able to buy a house with few problems, and get to decide on the neighborhood. Your quality of life, based on economic factors, will be better. No one can really argue that (I have not ever been to Oklahoma, but I am assuming that the cost of living is substantially less than Chicago and using this as an example). Many people would choose to go to Chicago because it is more "fun", without really ever seeing what life in Oklahoma is like. You may, in retrospect, love living in Oklahoma City. You may love Chicago. You may hate both. If you go to Chicago, you won't know what Oklahoma City is really like (and vice versa). But no one can argue that going to Oklahoma City would give you a better economic quality of life. Now, if you've lived in Oklahoma your whole life and hate it, by all means you know exactly what the cost (economic and lifestyle) of you staying there is. But most people will judge a city without really knowing what it's like, and I think that's the problem I am addressing, and it's better to go with a known factory like economic quality of life.
For many people, the advantage of a big metropolitan center is not simply the superior nightlife (though I do think that is a factor that can be important for quality of life, or at least it is for me). In big cities you're also more likely to be near people you know and care about. Nearly all of my closest friends have settled in NYC, and the opportunity to live in the same city as them (and be close to home as well) is a big plus for me. I'd gladly give up some extra cash to be able to see them more regularly.
Then again, my willingness to make that kind of tradeoff probably has something to do with my age (I don't plan on starting a family anytime soon), the value I place on my closest friendships, and the fact that I come from a relatively comfortable financial background. I could totally understand someone making the opposite choice.
Neuronix's case is just a reminder that big city != expensive city. (This is just one of the many reasons why Philly rocks.
😀) But even in your infamously pricey cities (NY, Boston), it does seem to me like life on an MSTP stipend can be comfortable, at least judging from numerous conversations I've had with current students in these locations. All the NYC programs, for instance, offer subsidized housing (which can have it's own disadvantages but at least helps to defray the main source of "cost of living" discrepancies between cities), and the slightly more expensive food/entertainment costs are offset by heftier stipends these programs provide. At programs where the subsidized housing is bad, it's still definitely a downside, but at schools with nice student housing (like Mount Sinai) I'm not so sure.
I'm currently trying to narrow down among my choices for MD/PhD programs, and, like almost everyone else on this thread, I care a lot about location and the quality of research in my (general) field of interest. But another factor which matters a lot to me, and which I don't think has been mentioned so far, is the opportunity to get meaningful clinical training before the last 1.5-2 years of medical school. I really don't like the idea of waiting 6 years before I have my first significant interaction with patients and start to get a sense of which specialties appeal to me. So I'm most interested in programs that would (A) allow me to complete a couple clinical clerkships before the PhD phase, and (B) give me the opportunity to do some meaningful clinical stuff during the PhD (should I feel like I have the time to do so). Since the major reason why I'm doing the dual degree program is so that I can approach my research from a clinical perspective, I'd like to already be participating in patient care before/during my PhD.
For current MD/PhD students, do you think this is a reasonable consideration, or is it bull****? Are early clinical experiences and clerkships in medical school meaningful enough that they can really change your goals/interests as a physician-scientist, or is it inevitably still like glorified shadowing? Do you think getting to do clerkships before the PhD can really be useful, or should I neglect this consideration entirely?