I wish someone from Wish would show up - Koryu in particular, since he was always my favorite from that series. Zima and Dita from Chobits showing up together would be wonderful. And I want Yue to appear. Also, anyone from RG Veda is always welcome.
Worlds...yeah, Celes would be nice. We don't know anything about worlds they haven't been to, so it's hard to say. I'd like to seem them go to a few more worlds after Tokyo, though, since I can never get enough of these places CLAMP dreams up.