Some people use destruction for multi pulls and some people use demo to ensure they don't get battered on (plus felguard makes solo grinding very easy)
I have levelled really well using affliction.
Put points in Lifetap, drain life, Drain soul (free mana when the mob dies) and max out corruption and Curse of agony. Fel concentration is a must as well.
Affliction builds using lifetap and drain life cause very little downtime (time to drink and eat) between mobs.
Use in conjunction with mining (increased stamina) and herbalism (free lifeblood heal so greater lifetap) and you will rape through the levels.
I used Ski but wasn't perfect.
Hope that helps mate.