I'm pretty sure the National Aviary is the best place to go look at birds on the East Coast. I'm a little sad that the penguins & giant owl aren't out for display, but you can see one at 10:30 and 1:30 (? - check the website to be sure) each day, at the free-with-admission bird show. Definitely go to the bird show.
Parents, please, hold your child's hand, and don't let him or her chase the birds. That ruins it for all of us; some of my favorite free birds (FREEBIRD!) have had to be locked up because of kids bothering them.