If you go to Kennesaw Mountain, and you like hiking, Pickett's Mill is close by. A very well preserved battle field, but as I said in order to see it all there is a lot of walking. Also in the area is New Hope Church, which is not really much to see other than a few markers, but you get the general idea of the lines of Gen. Johnston and Sherman. I think someone else recommended Marietta Cemetery which has over 3000 Confederate graves, mostly unknown, but if you have the time it is definately worth it.