The T fare is $1.00 now, by the way.
Another thing you can do is view Boston from above; I like to do that when visiting a new city. You can go either to the John Hancock tower (Copley Square T station, on all Green lines) or the Prudential tower (Prudential T station, on the E Green line). Copley Square is nice by itself anyway, with interesting churches - especially Trinity Church - and the shopping Newbury street to stroll nearby.