The Philadelphia Zoo is the best place to go for the animal experience of a lifetime.  I took my three children recently, and we had an absolute ball.  We got to see many different animals we did not know existed including those we were familiar with.  They also have a 'little people" zoo for the smaller children.  It was awesome.  We visited  one of the many informative animal shows they have a day and even got to pet some of the animals.  They also had a chance to ride and feed some of them.  We then visited the "treehouse", a gigantic manmade, hollowed, indoor tree!  (which you could also rent for a birthday party!)  Afterward, my children and I had a quick, but expensive, lunch.  (definitely bring your lunches)  We then decided to take a ride on the WPVI-6 hot air balloon.  We saw the entire city from up there!  (you don't leave the area, the balloon is tethered to the ground)  Before leaving, we visited the souvenir shop, strategically placed by the exit, where my children bought $179 worth of swag! (which actually was pretty cheap for the amount of swag they had)  By the time we arrived home, my children were happy and spent and so was I!