Our youngest daughter will be turning 16 in Jan. My wife wants to give her
a GPS unit for the car. My wife's logic is she would be a safer driver, if
she didn't knew where she was going, and was not looking for street names
and addresses.

It seems to me that another electronic toy in the car is just another thing
to distract her from watching the road.

Does anyone have any experience with GPS and teenagers?

and

Most importantly, does anyone have any experience buying a handheld unit
that has both maps for city driving and nautical charts?