Little late I know, but if you have not gone yet you should check the Fernbank site. I have a friend that is working there right now redesigning part of it and its not a small project. Some of the space maybe closed.
Don't forget the other Fernbank museum, the Fernbank Science Center, just around the corner. There's a planetarium and a telescope/observatory. Once a week (it may only be during the summer, but I'm not sure) they have public viewings through the big telescope. It's pretty fun.
There's also a small museum there, which includes some animals and an Apollo capsule!
When my son and daughter were little, I used to take them to Fernbank. We always had a great time! There was a dinosaur exhibit there that my son really loved. I think my daughter and I enjoyed the planetarium most. I think it had an extremely positive impact on their academic abilities, and we all learned to take a more scientific approach. -Mouldings