It might be interesting to create a map that compares Westfield back in the 1800s to how Westfield today. Another idea might be to try to look at wetlands in the area in general from past to present. This way we if there's any loss of wetlands we might be able to map the loss which might be useful in conserving them. Or possibly now that we've looked through a few historic maps it might prove useful to try to find historic buildings or identify historic areas so that a map could be created to help the conservation and preservation of such areas and landmarks.
Finally i found some of the very old maps of Boston to be insightful on the earliest development of the city, and how the city has expanded and the land itself has changed do to dredge work. This might also be a topic to map where we could map the changed land mass or map the development of boston over several time intervals.