Must-to-do in Atlanta

Hi Internations in Atlanta~

I'm Narae from DC and going to Atlanta in April 30th to attend my friend's wedding there.. I am about to book my flights..

1) So would you recommend that I should take late-evening flight going back to DC instead of 11:00 am one?
2) If so, what should I do to spend my Sunday afternoon there?

Thank you so much in advance!

(if there is any Internations event on Sunday, that's the place to go, right ;) )