There is a shortage of hotel rooms in Boston and has been for many years.  The only real slow season for this city is in the dead of winter.  The rest of the time rooms are generally at a premium.  One of my favs has had very good luck with Price Line's "hot deals" hotels (just under $100 a day, in the city) but the hotel you get is probably not going to be in the busiest part of town.  If you want business from the guys who are in town the price line option is still better than going to the burbs.  That being said, a lot of guys prefer the suburbs over going into the city.  I've known girls who spent a few days downtown and a few in the suburbs during a visit.