I spend a lot of time in New York. I've been to both Boston and Seattle, although not enough that I would consider myself an "expert". I wouldn't want to live in NYC because I just couldn't get used to the whole "urban jungle" massive population density feel. It's almost like you're just a single cow in a massive herd of cattle when you're in Manhattan. It's fun for short periods, but after several days you get tired of it and just wanna go home, and you know that "home" could never be a place like that. Don't get me wrong, I like cities... I lived in the Georgetown section of Washington, DC for many years, and I live in Houston now, but Manhattan has a "rat race" feel like no other city that I just don't like.
Seattle is just too dreary with too much overcast and rain... I'd be depressed all the time. Boston is just too "northeast/blue collar/old-world attitude" that I don't like, plus I'm not a fan of cold and snow.
Boston is extremely expensive, and there is a lot of "old money" in the city. I'm not sure if you spent time in the Newbury, Cambridge or Back bay areas, but old world attitude is one of the last things I think Boston projects. Architecture wise, yes... but I don't think its inhabitants are "old world". Actually, Boston was just voted the most tech savvy city in America (
http://www.usatoday.com/tech/techinvestor/industry/2008-06-19-milken-tech-report_N.htm), and with over 70 colleges within or surrounding the city, it is a very liberal, and forward thinking city these days. Can't disagree with you on the snow - it sucks, but we have a great summer, spring and fall....plus the city is on the ocean, and the cape is less than an hour away.
I think all city's have a blue color population, and Boston is no different. However, the city is so expensive, that class is pretty scarce within the major metro areas. You see a ton of doctors, since we have so many hospitals.... A lot of young professionals, college students, and grad students. Every fall, the populaton swells by over 200,000 when all the new college students arrive. Next time you visit the city, check out Newbury street, Back Bay, Harvard square and the South end.
I think Seattle is a great city, but like you, to rainy for me.....NYC is a good time, but I agree with you, to large for my taste. I wouden't vote Boston as the best place to live in the US - ( the winters, and the cost of living are harsh), but I would rank it in the top five.