I've seen pretty much every combo often enough to not be impressed by it anymore, or do a double take. Looking at my Fem Pandaren Warrior is pleasing and new enough to make me consiously watch though.
worgen warlock/rouge/death knight.
dwarf warrior (thank you J.R Tolken).
NElf female has to be the most underrated race/gender in the game. They look ugly until you get them in higher-level gear, though.
Same goes for Draenei Males. They look horrible until they have some real shoulderpads on.
"I quit WoW."
If I say it's Azshara next enough times, eventually I'll be right. So here we go again. It's got to be Azshara next, so get ready for the Sylvanas expansion we inevitably get instead!