What's there to do in Atlanta?

My last trip was over ten years ago. I went to the World of Coca Cola, the Georgia state capitol, the CNN studio tour, Lennox Mall, some art museum that I can’t remember the name of, ate at the Varsity, wandering around the Georgia Tech campus, and drove to Athens and Stone Mountain.

I’ll probably be going over a weekend sometime between Jan-March next year. I probably won’t have a car, so I’ll want to stick to the MARTA system or walking distance of Midtown. Anything new I should see? I’ll probably be by myself during the day, but meeting with friends at night.