National Aviary is a very special place. To get the full experience, I highly recommended attending the show which I think is about $5 more than general admission. The show's hosts are lively and full of energy sharing all sorts of fun facts and history of various birds while the birds fly through the arena. And boy do they get close. An owl pretty much slapped by boyfriend in the face with his wing (and he didn't mind). But if you're not looking for that immersive of an experience don't sit in the middle or towards the back since that's the path most birds fly through.
There are about 3 or 4 different climates in which to see a number of birds used to those climates. They are all so remarkably beautiful. The staff in each room are very knowledgable and willing to share their wealth with you. :)
Also, don't forget to stop by the gift shop which is pretty cute.
I went on a weekday. Even though it's a family friendly place I didn't find that kids were "running around all over the place" like some of the Aviary at Night reviews had mentioned. We had a really good time. A great place for the family or a date.