There are plenty of same day half price tickets in Atlanta, and two places you can get them - the Underground Atlanta Vistitor's Center and Lenox Square Guest Services. You can also buy them online and in advance.
Atlanta's Metro makes it easy to get around too. However, if the word "Peachtree" is in the address, be sure to note exactly which Peachtree, since it seems about half of Atlanta's addresses use the word. There's a world of difference between Peachtree Street, Avenue, Place, Way etc.
Atlanta Performs website