Hi,
I'm a 4th year HMS, stopped by the allopathic from for old time's sake
funny how the discussions don't change much over the years. I can speak to Harvard, won't say much about UCSF since I didn't go there...
So to start, unless finances is an overwhelming, burdoning thing on you, I'd say don't worry about it, don't let that make your decisions for you, use other metrics instead, medicine is heavily supported and you won't live a life of poverty, or anything close to it, unless you explicity choose to do so. You won't be any significantly more or less financially solvent in 10 years having gone to UCSF or HMS. Plus HMS is very generous with fin aid, and once you're here, it's surprising how much easier it is to get scholarships, grants, etc, I'm graduating with a debt of $40K, I think ave is like $80K, it's not great, but not horrible... really, try not to make finances a deciding factor, things work out...
Family and weather are reasonable concerns. These are personal issues, some people come to Boston and get depressed, that sucks, if weather is that important to you, it's important you stay in good climate. It can be hard to fly coast to coast. It's 4 years, for some that's too much to bear, for others, it's ok, a new experience...
At risk of being flaimed over this, I'm going to mention the name game. Harvard has a great rep, this is true. If you're planning to stay squarely in medicine, frankly, I'm not sure you get too much an advantage from Harvard vs UCSF. If you have any interests outside of medicine, I think Harvard helps. I really think non-medicine people just see Harvard as an icon of something really impressive. Accordingly, it gives you recognition and makes a good first impression to help you convince people when you're thinking about projects that you're a person they can trust and support. This comes in really helpful whether you're applying for a scholarship (for instance, check out Soros Scholos,
http://www.pdsoros.org/), trying to start up a small public health project, or do an international summer experience or 4th year experience. Plus, Harvard gives incredible internal support to it's students. If you want to take a year off, you're almost guaranteed a a ~$30K support for that year as long as your project is reasonable. I'm not sure UCSF does that, it may, I really don't know, best to ask UCSF students about their side... Ultimately where I'm going is that HMS and UCSF probably open the same doors if you talk about most medical oriented careers, but when you start talking about potential somewhat less traditional careers, HMS I think definitally opens those doors more than most other schools (schools in this category are schools that the "general public" would find to be most impressive, places like Yale, Hopkins, Stanford, Harvard, etc), and so that may be worth taking into consideration.
The whole thing about HMS students being clinically poor is an oversimplification. HMS students tend to be, on average, more multi-interested in kinda complicated, multifaceted careers than most med school grads, and those people, just by virtue of having their interests and time split amongst multiple things, do tend to be a little less pure clinical prodigies than others who are focussed on purely clinical work, for better and for worse. There are some here who are purely clinically focussed, and they're probably as good as any other strong clinical graduate at any other school. There comes a point where there's only 24 hours in a day, and you can't be perfect at everything...
I've absolutely loved being at HMS, it's a great crowd, fun city, and professionally a great experience. I've been able to get involved with some really awesome research and other international health projects and random other things that I'm not sure I would have had the opportunity to do at very many other places. I'm not saying that such opportunities are not available anywhere else, you can probably make things happen at any medical school in the nation with enough motivation, and I'm sure at UCSF it wouldn't take much extra work than it would at HMS to do such things, but definitally at HMS the opportunities are like low hanging fruit. Good luck!