All advanced classes should have their own individual look with armor sets. Not just different colors.
All armor sets should be designed around the species. (i.e. Tauren, Forsaken, Worgen, etc. like blizzad does in WoW)
some pictures:
http://fc07.deviantart.net/fs19/f/2007/244/9/4/Sith_Empress_by_namesjames.jpg
http://images1.wikia.nocookie.net/__cb20100615163921/starwars/images/5/5d/Sith_Legacy.jpg
http://monsterscifishow.files.wordpress.com/2008/09/starwars_sith.jpg
http://images.wikia.com/starwars/images/b/be/SithStalkerArmor-TFUUSE.jpg
http://images3.wikia.nocookie.net/__cb20081202053633/starwars/images/e/e3/Sith_trooper_concept_art.jpg
http://3.bp.blogspot.com/_XdP6Lp2ceqY/SwTSznfyTyI/AAAAAAAADgs/eeScgGc-qt4/s1600/altair.jpg
http://reignguild.net/gallery/plog-content/images/star-wars-the-old-republic/concept-art/timeline08_malak_revan.jpg