The restaurant is on the very top floor it is fairly new I believe. It could have been a vent but it looked like a Fedelcode on a building next to the steam plant. I actually saw the MD mount on the hurt building but the siren is gone :(. You should go to the restaurant however it can be kinda price...
Yes, Grady as in the hospital. I got a shot from The Sundial which is a resteraunt on top of the Westin (big glass cylindrical building in case you are not familiar with atlanta) you can go up for free or eat lunch or dinner there. It revolves.
All I had was my iPhone 4 and the telescope . I saw some really cool stuff like the huge rail yard along with Emory. I recommend you go there. I also thought I saw some type of Fedelcode near Grady . No telescope reached it, nor did my phone.
Two things. There is a remaining thunderbolt at oak grove elementary school. And also I got a picture of the Richard B Russell thunderbolt trough a telescope at the sundial. Sorry for the bad quality.