Sacred Haven of Debauchery

The key word here is _play_. And I don't want to play; I want to tinker with the editor.

Playing from the start means having the option to choose an alien instead of a human during the generation stage. =/
Again, there aren't that many character types that look significantly different. Even the fairies only differ in the aura behind them. Mages don't differ at all. Genies have a different skin tone, which is easily achieved by installing a mod. Most of these so-called "cool races" differ primarily in additional abilities during gameplay, rather than in their unique appearance.
Again, if you want a character type that is not available from the start, you start playing, change it with one cheat, and then open the appearance editor with another cheat.

Added 3 minutes later
Oh yes, and in the fourth game, you can dress any sim in any outfit; the gender restrictions have been removed. This also positively affects the possibilities for creating characters.