I lived in Boston all through grad school and worked there for a couple years afterwards. The city is dark, insular, and segregated, with very harsh winters and short summers; the year I moved there people were wearing heavy coats and gloves in October. I wouldn't go back there for a job at Harvard or MIT. 
Thats your opinion, I would have to disagree. Not sure how you could say a city that legalized gay marriage, and has a massive college population is segregated and insular, but you did say San Fran has a nice climate, so to each his own I guess. Most colleges here have a large international population, and they all live in the city. Tons of foreign doctors, lawyers and professionals as well. I would think you would agree if you spent time at MIT, or Harvard? As for Boston being dark, it's not even close to as dark or rainy as Seattle, which many consider a top city.
The city is 80 percent young professionals, and college students. The winters are long, but I enjoy snow, and change of season. Fall and spring are great seasons here, and I enjoy the color that comes with it. I wouldn't call a four month summer short, either. I bet it's hotter in Boston during the summer than it is in Frisco. It's consistently in the 80's all summer long.
As far as a great city goes perfect climate is a portion of the puzzle. From a technological standpoint, as well as Career opportunities I can say for a fact Boston is among the elite. The city is pretty trendy, and there is alot to do. It's not Hawaii, but you don't go to Hawaii to establish a career. There is a reason people come from around the world to attend the colleges, and seek medical attention at the hospitals.
Please dont take offense to this, but your top list was a bit swayed towards the gay lifestyle ( which is fine).
