Here be spoilers!
Where is everything?
Most of the places depicted in the Grunt's Grimoires don't exist.
Please do not wander around Atlanta trying to find them.
The big exception being Stone Mountain park. The Battle of Stone Mountain takes place near the summit at the end of the walkup trail.
But for completeness:
The Cotillion is more or less where the Masquerade used to be, on North avenue just west of the railroad overpass.
Connie's house is in Little 5 points, somewhere between Moreland, Elucid, and Freedom Pkwy.
Tyler's house is just outside the perimeter, somewhere between Glenwood and Covington Hwy.
Warwell's is southeast of Stone Mountain park.
The Blue River runs from Athens to Milledgeville. The site of the massacre is a few miles East of Warwell's.
The Waffle Crossing where Loretta and Grover work is off of sr78 just before it becomes Scott Blvd.
Samuel's is south of the Emory campus.