Amazon wishlist for the new expansion, just add your own. There are certain things I would really personally love to see to keep the game interesting and that Christmas eve giddiness going. From realistic to daft, put your own here!
4 more character slots
Roc mounts for the alliance (horde have bats and wyverns and dragonhawks, alliance have gryphons and hippogryphs, rocs would be a nice addition)
A new class (be it necromancer, ranger, demon hunter or whichever)
New races be it ogre hordes or alliance whichever be it what it may highelves, drakonid, furbolg, kobold or grell
Some new down to earth armour sets, a warrior set to make you look like a knight, a rogue to make you look like how an assassin possibly would, something with narrow downed shoulders, helms, belts something with more realism i guess?
A new secondary profession which is purely optional
proper night and day
Zone wide seasonal changes, winter, spring, summer, autumn. (the pre-saved zones which load, have discussed this before and it's easily done)