Even though I live within two hours of Chattanooga, I had never been there. I enjoyed Look Out Mountain, Ruby Falls, and the Incline Railway. I was not impressed with the IMAX threatre, Children's Discovery Museum, or the Aquarium.
I took my six- and seven-year-old nieces. They were bored with the Discovery Museum which is interesting since it is for kids. The one area they really liked was the Dinosaur Excavation area. Kids get to dig in the sand and uncover fossils of a dinosaur.
The Tennessee Aquarium has a lot of build up -- everyone told me how wonderful it is. I think it might be a little too large for younger children to fully enjoy.
The kids did get into the outside stuff like Look Out Mountain and Ruby Falls.
The great thing about Chattnooga is that it is fairly inexpensive great family vacation.