I haven't been to too many aquariums, but I've noticed that they all smell the same. Also haven't been to an aquatics show in a long time, but definitely think they've gotten cooler in the interim.
I liked Shedd's layout. At the center is the huge Caribbean reef tank, off which smaller tanks (exhibits?) are branched off, divided up by the type of water. On the lower level are the bigger features - whales, dolphins and sharks. (Though the otters got a lot of love to, because they're cute, I'm assuming.) Considering how b busy it got, I never felt cramped. I think that's a credit to the layout and design of the aquarium.
The site wasn't lying when they advise to get there early. I left around noon and the line to get in the door must've been 100 deep, and growing. They also weren't lying about the visit length. The site says the average visit takes around three hours. I was there for four. Totally worth it. Based on the popularity of Shedd, I'd guess I'm not alone there.