The John Jeffries House is pricing out at $139/$148 for the dates you quoted and it is right in the middle of Beacon Hill. Continental breakfast is included and many of the rooms have kitchenettes. Beacon Hill is a good location and you can walk to Cambridge from there and you are also located very near the Red Line. I haven't stayed there myself, but used to book corporate guests here and they were always very pleased.
http://www.johnjeffrieshouse.com/