Hello KBLovesDisney!
A good website is Cruise Critic . I put a link just above this post.
Let me try and help you here though with some random thoughts.
Carnival Cruise Line attracts a younger crowd and because of its entry level value price it tends to have a more party orientated crowd than some other cruise lines. We went once on Carnival from Port Canaveral. It was ok......but we like Royal Caribbean Cruise Line better. We've taken three cruises with Royal C. Their price is LESS than Disney Cruises but more than Carnival......right in the middle
Royal Caribbean has a ship that sails from Baltimore MD....so that is north of Charleston SC that you mentioned......and as I previously stated, Royal Caribbean also has ships that sail from Port Canaveral which is east of Orlando Fl. (Carnival, Royal C. & Disney all use Cape Canaveral' Cruise Port)
So I don't know if you are will to go north or south of SC to widen your choices or not.
Let me know if you have any follow up questions.
www.royalcaribbean.com