Rane

Hearthstone in Shattrath is absolutely invaluable once you leave the 1-20 areas where'd you normally hearth to the nearest inn or capital.

For casters, you really want to keep an eye out on the AH now, a lot of cloth items have lost their useless stats and have gained spelldamage. I was pleasantly surprised by it, at least. The Shadoweave stuff and several quest rewards are awesome upgrades now, I'm currently running 170 shadowdamage on my lvl 45 warlock, leveling is insanely fast, everything dies from 3 dots. Tag, hit 3 buttons, fear, run to next mob, hit 3 buttons, fear, etc. It's crazy.

I'd love to do instances since the upgraded loot is nice, but I outlevel them before I realise it now and my lvl 70 guildies don't like running old world instances anymore so I generally just skip them.

*edit* Don't forget Dustwallow Marsh. They're good grinding quests and only Jarl's questhub requires a fair amount of running around, all the other stuff is fairly closeby to their questgivers and it's all mob grinds. They also have an awesome pair of spelldamage cloth boots as a quest reward, at least Horde, for the questchain involving the Black Dragonflight in the Stonemaul ruins.