The Boston "T" subway goes to Somerville within minutes of downtown Boston. The orange line hits the working class area and the Red line hits Davis Square which I find the most livable, lively area in Boston. This is the area I know best and would love to live there in a heartbeat! within three blocks of the metro are some of the areas best selection of affordable places to eat (Annas Taqueria is my favorite) a real cinema with affordable tickets, a bowling alley, Boston sports club, tons of cool cafes and places to hang, tree lined streets converge to the large community gathering center across from the "T" and cinema. The "T" is underground for the cold cloudy rainy snowy winters which seem to last till June and it has frequent, fast service to all the cool stops in Cambridge (Porter sq, Harvard sq and Central sq) on the way to downtown Boston. Basically you have access to everything needed for a fun, comfortable life in a nice environment with quality rapid transit access to tons more options. Davis Sq. is the closest center for Tufts University so its like living in a pretty college town with access to a major city with a 15 minute subway ride.
Every summer my wife and I travel up to Somerville from Boston and spend a weekend or two. We hop on the train from Boston and it gets us there in less than an hour. Somerville is a cozy little city, very blue collar, it's a bit grimy sure but that's what makes it great. Somerville is a very down to earth kind of place, it's good to get out of Boston once and a while and see how 'real people' live.
My wife is a huge history buff too she really loves all that stuff about the revolutionary war, and Somerville is one of the best places to go for New England history. There are a great number of museums and historical sites to visit in the city, and believe it or not Marshmallow 'fluff' was invented in Somerville. There are lots of cabins and cottages to rent just outside the city if you want to spend a weekend in the woods, and some charming little bed and breakfast inn downtown as well. If you want to get away for a nice quiet weekend trip I would definitely recommend Somerville.