Don't know about Atlanta - mine was at Lime Rock. I'd guess they have the same setup though. The mechanics are there super early so I'm sure people will be around.
I got lucky with the weather we had. First 2 days were beautiful and the 3rd gave us the opportunity to drive in the rain. Entirely different line through the corners. I was actually quite happy for it to wind up like that. During the last lapping session it was raining on one end of the track and drying out on the other.
After each session I would also suggest leaving enough time for a 2+ hour nap before dinner plans
Steve