Be ready to brave the parade of strollers and screaming kids when you visit the Biodome. Ok, it wasn't that bad but it was pretty crowded with many families.
For Chicagoans, it's like the Garfield Park Conservatory but with animals, and perhaps a dash of the Shedd Aquarium thrown in. Monkeys, birds, fish, snakes, alligators, starfish, etc. and the majority didn't look too miserable. Without fences/cages you can get pretty close.
It's right off a metro stop and $16/adult for just the Biodome (there are other packages). It was a good change up during out trip--seeing animals and vegetation during a very cold December.