I too would love some more hair options, and I'd REALLY love height and other body modifying sliders. They could do something similar to Phantasy Star Universe's body modification, which allowed for unique body types without having the ridiculously shaped characters you see in WoW or Aion.

Hair based on characters from other FF games would be interesting. Humorously enough, Aion already did have Cloud's hair (the Advent Children version) and it was awesome.