Any cell phone can call 911 and towers to triangulate location. This is HIGHLY INACCURATE, and thus police don't trust it.
If your phone is GPS equipped, check to make sure GPS is enabled when 911 is dialed. Its not on by default for every smart phones. Newer ones, I noticed it is.
Otherwise, if you want friends and family to be able to see where you are, by all means leave GPS on and use one of a dozen apps that allow tracking with permissions.
The newer smart phones batteries are very good at holding charge for 24 hours with all the bells and whistles on, and see's high use. I would not turn off GPS just to conserve battery, unless you really have a need to conserve battery! And while one travels, its all too easy to have it on the charger the entire trip.