Don't name your daughter after a city. She'll only be laughed at or behind her back. She'll resent you for it. Think
Paris Hilton, hence why you've never heard of it.
It is without coincidence that traditional names are now the most common baby names. The generation of new age/modern names are having children and naming them biblical or other traditional names. Especially the children of hippies, they never liked their names.
Why not
Charlotte,
Carla,
Carlotta or etc?
You could call her
Charlie for short or
Lottie.
Here's a list of more related names:
http://www.behindthename.com/name/charlotte/related
Keep in mind that Charleston was named after
King Charles II.