All we've seen so far from him is a statue and his grandson. I think it's time we see Zuko and not in some slapstick flashback scene, but as how he is now. An old man, and if that is not given us, than at least give us a picture of him in the newspaper while another character is reading it.
I think it's time to show us the part of the Spirit World where the Sky Bisons gather, because I want to see Appa.
I know that you guys all love Katara and so do I, but she's getting old. I want a scene where she dies and Kanna comes to her. Saying that they look a like now, more than ever.
Now that the Spirit Portals are open and everyone can just get in and out, let us visit Momo.
I would like to see Gyatso when Tenzin enters the Spirit World without his body. So Gyatso can say 'Congratulations' to him. Saying that he is just as good as his father.
What do you guys think? Who would you like to see return?