Ruby Falls is a blast! Steven and I went and really enjoyed the cave tour! I have also done the zip-lining and rockwall climbing if your feeling a bit adventurous.
The Tennessee Aquarium is always a fun time, we have been a few times. You get to explore the ocean and the river. They even have an IMAX experience where you can watch a movie about the different aquatic topics.
Rock City has the best views! You can even see 4 different states from one point of the mountain. They have guided tours or you can just experience the nature on your own. They also have seasonal adventures, since it will be October they will have the Enchanted Pumpkin Patch going on.
If you are looking to get some coffee and let the kiddos feed some Alpacas this will be a great place! They also have a little boutique you can buy handmaid gifts.
If you're over 21 and want to see how whiskey is made you should visit the Chattanooga Whiskey Distillery. They have tours and tastings as well!
Unfortunately we don't have a review of the zoo but have always heard amazing things! If you check it out let us know your review :)