The City Pass is a great way to start with Atlanta! You get passes to the aquarium, world of coke, and Inside CNN, zoo and Atlanta historical centers. I would try the Hyatt hotel as well.
I live in Middle Georgia. I did the donation request thing last year for our military holiday party and am working on it again this year. The local places that have given are:
Fox Theater - two tickets - Faxed request...info and # on their website
Medieval Times - two dinner tickets - Fax request - info and # on website
Stone Mountain - family pack of 4 tickets - Fax request - info and # on website
Zoo Atlanta - 4 tickets - Mailed request - Address on website
Georgia Aquarium - 2 tickets - applied online at their website
These are pending:
Six Flags - no response yet to mailed letter
Braves - no response yet to mailed letter
Atlanta Falcons - no response yet to mailed letter
Lake Lanier Island - emailed but no response yet
Imagine It! Children's Museum - no response yet to mailed letter