Hey you were pretty close to where my wife and I live! we live about 1hr20 minutes up I-75 from Chattanooga. Rock City is definitely a very unique place and the views from Lookout Mountain are incredible.

There's also an underground cave system near there and there's an attraction called Ruby Falls which includes a pretty long hike for a cave and it ends at the falls which are about 60 feet high if I recall correctly. It's been awhile since I've been down there to Chattanooga. It's a pretty cool city. Glad to hear you all enjoyed it!