I like Rafiki's Planet Watch a lot. Be aware that they do veterinary procedures mostly in the mornings. And I was told just this morning that they don't do them on Wednesdays any more - such a disappointment for me, since I went there specifically for that this morning!
One thing you can do is to have one of the cast members call on the radio (walkie talkie) and find out what the schedule is for the morning. I was asking a CM by the front gate if she knew what the schedule was, and she offered to call for me.
Other things to do at Planet watch are the petting area (you can brush a goat!); talk to a CM who is preparing food for the animals; watch a small stage presentation where the zookeepers bring out animals and talk about them (often things like reptiles and birds). It's quite a fun area, at least in my opinion!