The Biodome is a great option for a half day with the little ones. It's a fraction of the size we are used to with the zoo in our town (Toronto), but honestly with a two year old that was a blessing.
Designed as differing ecosystems there is quite a bit to see here. It's about 10-15 species per section, with most allowing a close up view.
It's definitely more of a kids outing then one for adult animal lovers. Admission was free for our 2 year old, but close to 40 for two adults. Parking was nearly $20.