If you go on spring, like I did before, bring more jackets, scarfs , and their friends. Because it will be very cold. Be prepared to take taxis many times.
Make sure you go to 2 top universities there, Harvard university and MIT. Go to their shops, buy some souvenirs for your friends. Boston is very famous as student's city. One of the hotels there set their rooms with formula themes. So, you can sleep with a blanket that is full with math formulas =).
There's one nice cafe in this city that is usually used by university students for celebrations or just for hanging out. Try it! Unfortunately, I forgot the name =(.
Enjoy your trip =)