/Parentcentric view to follow/
While Brookfield is a great zoo, I would take a 2-1/2 year old to LP.
Why? Because they will have just as good a time whether they are at one or the other, they are not critiquing the zoological arts or getting pissed that the rare elusive _________ that only Brookfield has is there or not. They are looking to see some animals, walk around with mommy and daddy, eat some yummy popcorn/lemon chill/ice cream by the lagoon/ etc.
While Brookfield is larger and nicer, it is larger! A tired, footsore, cranky parent will not a happy camper make. After seeing LP Zoo, you will still be rested enough to deal with the rest of the day.
I’ve taken my kids to both numerous times and they enjoyed both as well. Plus we took the money we saved on entrance fees, bought some bread and fed the ducks at the S end of the park Lagoon, or rented a paddle boat and went around the little islands.
The Childrens Zoo and the Farm in the Zoo are also Huge hits with the wee ones - they can relate to cows that go Moo, piggies, and horses more than the esoteric animals that interest us big’uns so much.
There is also the Arboreteum at the NW corner of the Zoo which is really cool as well. Actually, its sweltering, for coolness zones, the underwater viewing area at the seal tank has great A/C vents and the Regenstein small mammal house is quite chilly - plus the bats area is rockin and the new addition to the entire house is really cool with little vignettes of rainforests, Australian sandy bits and the like.
Hope this helps.