I need help with Birthday Ideas?!?

Me & 4 of my closest friends are going to Atlanta for a few night for our 16th birthdays, over the sunmer. What should we do while were down there? I have grown up around Atlanta & have seen most places but where do you think the best places to go for your birthday would be? No shopping please. We were thinking about six flags & maybe a spa... But I have no idea which spa, any recommendations would be greatly appraciated. Also what places would be cool to check out while we're there? Thanks in advance (;