I've gotten most of my iron in Stonetalon and Thousand Needles but then I'm a Troll so those areas are easier for me to get to. Those areas aren't too tough for a level 30+ though so you might consider them.
The best place in the game to mine iron is in the arathi highlands, and hopefully your server doesnt have too many other miners who want iron because thats a hot spot for that vein.