Charleston is a great city for walking around. For street photography: the market area, many historic buildings, rainbow row, horse-drawn carriages. On the outskirts of town there are also a lot of plantations that you can tour, most of which have beautiful gardens and marsh areas.
Magnolia Gardens has a great rookery and swamp garden for birds such as blue herons and ibis, etc. There's also the Caw Caw Interpretive center which is a great nature preserve with wide open rice fields, an old plantation with hanging moss trees and a swamp walk through.
There's also the USS York which is a retired aircraft carrier open for touring.