You cannot leave Atlanta without checking out the BeltLine Trail! The Eastside trail starts at Piedmont Park and provides a great opportunity to see some of Atlanta's most vibrant shops, restaurants, and bars, which are peppered alongside the trail between parks and public art.
Stone Mountain Park is great for hiking, trail walking, and other family-friendly outdoor attractions. Don't forget to take a picture when you get to the top; you can get a good look at the Atlanta skyline on a clear day!