When they first come to the game, many players instinctively know what they want to play. For me, my first love was, and ever shall be, my female tauren druid, the lollopy-gaited, bemused-emote, hoarse-voiced heifer. I can't even explain why she appeals to me so much, because her casting animations are relatively boring, and the female tauren voice actress sounds like she's nursing a 40-pack-a-day habit. It matters not. She is loved.
When it comes to other characters, though, I can usually point to someone or something else that inspired me to roll that alt. Big Red Kitty made me want to play a dwarf hunter (now level 67) with a Frostsaber Pride Watcher. This video made a tauren shaman look awesome, so now I've got one at 71. And it was World of Roguecraft, oddly enough, that made a male undead warlock (as opposed to rogue) look like it could be fun; the scene with the warlock and rogue taking a stroll around the Lordaeron ruins with the warlock's imp toddling beside him, for whatever reason, sold it for me. When I look around my list of alts, for each I can name something or someone who just made that particular race/class combination look cool. Who or what inspired you to play the races and classes you're playing right now?