We flew into Atlanta got the $7 pass for 4 days of unlimited trips. We all hopped onto the MARTA. It was approx 25 minute ride from the airport to the Peachtree station which was just outside the hotel. We stayed at the Westin Peachtree (I think that is the correct name).
Being one that really felt lazy the first morning of competition I did take the MARTA. We had to go one stop west then get on another train and go one stop south, if I remember correctly.
I was really awake after the competition so we decided to do the 6-8 block walk back. We determined it was a lot quicker to walk then to get on and off trains.
On Sunday we took the MARTA back to airport and flew home
If you are flying into Atlanta get the MARTA 4-5 day pass. It is worth the $7.
If you are not flying into Atlanta it may be nice to get couple of passes so that people can go around town quicker and get supplies or materials to fix robots
*My 2 cents worth*