The trolley tour of Boston, offered as an optional, is the best way to see the entire city. Take it at your own pace, but I would suggest stopping off at the USS Constitution and Fenway.
For ladies I would definitely recommend finding some slightly nicer than normal black flats... I bought some in Prague for super cheap and still wear them all the time!
Definitely worth doing if you are in any way interested in Ancient Rome - the guide is a wealth of knowledge.