Thanks for the responses!
We will be staying in downtown Atlanta at the Loews, but I will have a car. We should have a pretty good amount of time - would need to be showered and ready to be shuttled from hotel at 6pm. I hadn't thought of the potential for a 5.5 hour round...
And the potential for a 5.5 hour round is certainly in play.
With all due respect to the courses, the people playing, and other posts, I'd stay far away from any of the city of Atlanta courses on a holiday weekend Saturday. North Fulton/Chastain Park is interesting and has some cool history, but it will be a pace-of-play disaster that day. The other city courses are not worth the trouble.
I'd easily prefer Wolf Creek over Stone Mountain; the drives and prices ought to be pretty comparable, but Wolf Creek is a better golf course. If if you do go to Stone Mountain, the advice to play Stonemont and stay away from Lakeside is spot on. Heritage is also pretty convenient to downtown, and in the same price range as Wolf Creek and Stone Mt.
If you want to get up really early and make a bit of a drive, the best bet might be Cobblestone. It's about 30 miles from where you are staying, but it's an easy drive, a good value, and a highly regarded course that has/does appear on a lot of public course ranking lists. (It's too bad that you likely can't get to Arrowhead Pointe, but that's another story.)
One other that I'll mention. The Frog would be a little bit longer ride (40 miles) but also very easy driving out I-20 on a Saturday morning. I get killed every time I say this on GCA.com, but it is my favorite public Fazio course that I've played. First hole is kind of weird; after that it is a very solid and underrated golf course.
Hope some of that is helpful, and good luck. Unfortunately, you are not coming to a public golf mecca, unless you are willing to do some serious mileage.