When I set up my tour last year, they said dress business casual. So a nice shirt and slacks should be fine, but wear a suit if you are more comfortable. If you could also hold off on touring the campus until a few weeks after classes start so you will be able to meet the students. This was the biggest selling point for me. They were all so excited to be there, it was the main reason the I applied.
GA-PCOM 2010