Well,I just came back from a great visit to the Tennessee Aquarium. If you're in the Southeast and have never been, you really should go! The admission is quite reasonable—only $17.95 for an adult—and it's well worth the time and money. (I'll definitely go again, even though we'll soon have our own aquarium in Atlanta.)
Your aquarium ticket covers admission to TWO buildings: River Journey, which traces the Tennessee River from its origins in the mountains all the way to the Gulf of Mexico, and Ocean Journey, which has fewer exhibits but two big sharks as the main attraction.
If you can, be in River Journey around 1 pm. That's when they feed the fish in the Gulf of Mexico exhibit (the really, really, big, multi-story tank in the center of the aquarium). That includes the enormous sea turtle, the rays, and the small sharks. It's fun to watch!
My favorite permanent exhibit is the river otters. Unfortunately, one of the two original otters died about four months ago; the remaining otter was sleeping when we visited. Hopefully they will add more otters soon!
One surprise: the seahorse exhibit! When I was there two years ago, the exhibit was due to end soon, but apparently they changed their mind. I took tons of photos of the seahorses and seadragons. The seadragons are proof that dragons DO exist–they're just a bit smaller than we thought, and don't breathe fire!
I'll post my opinions on the rest of Chattanooga later.