I would add ....
Lunch or dinner Fleet Landing
Breakfast or lunch Marina Variety Store (on the dive side, but great view.
For a fun dinner, Fuel across from Hominy Grill (which is always busy except for dinner - the Hominy Grill that is).
These are all downtown, but there are so many places around the peninsula West of the Ashley, James and Johns Island and Mt Pleasant!
The Farmers' Market Saturday morning is a must. A harbor tour/trip to Ft Sumter will give you a great view of the city. Just walking around South of Broad, the Battery, lower Meeting St.
Or take a carriage tour.
Please let me know if I can be of any assistance.