Athens, Georgia is a charming university town. You can learn more about Athens from Wikipedia and other sources, but here are some highlights.
By May, it will be warm enough in Athens for short sleeves and summer wear. Wear what you're comfortable in (business casual is what most people will be wearing) and be sure to wear comfortable shoes so you can walk downtown in the evening for dinner.
Athens has many wonderful places to eat. The Athens tourism bureau has a list of restaurants. There are also coffee shops close enough to the Classic Center that you can pop in and out between sessions. Feel free to add your own favorites here!
For coffee, the best place in downtown is Jittery Joe's Coffee Roasting Co.. It is not far from the Classic Center.
Some favorite places to eat downtown are Harry Bissett's New Orleans Cafe and Oyster Bar, The Last Resort, Clocked, The Grill, Casa Mia, Depalma's Italian Cafe, Gyro Wrap, and The Basil Press. They all serve lunch and dinner but The Last Resort does not serve their delicious creamy grits during lunch. Farm255 (dinner only) has had excellent reviews and serves seasonal and sustainable food. Close to downtown are Mama's Boy, Big City Bread Cafe, The Grit, Cali N Titos (cash/check only;BYOB),and Siri Thai Cuisine. Traditional long time Athens favorite restaurants include The Varsity, The Grill, The Grit (vegetarian), and Wilson's Soul Food. There is also Five and Ten which is an upscale restaurant serving dinner and brunch on Sundays and has been given excellent reviews by many including The NYTimes.
Athens has a lively pub scene. This pub crawl of Athens features stops through the town's best pubs, including Copper Creek Brewing Company, Athens' own brewpub that always has several of its own beers on tap, and The Globe, voted by Esquire Magazine in 2007 as one of the best bars in the U.S.