Not familiar with downtown Atlanta I would say probably not a good thing to try. However, there is parking available for buses that would fit a TT and TV. My kids went on a field trip and we stopped there and there was no issue in getting the bus in and out of the parking lot. But of course our driver was familiar with the area.
If you really want to I would call them and tell them which way you are coming and they could give you directions on how to get into the lot. It is just a matter of knowing how to go around the block.
