I wonder how you get oom so easily with classes you mentioned; lock, priest, druid and shaman. All of them have mana regenerating abilities and any time I leveled one of those, I had close to zero downtime spent drinking and eating. Aff or demo locks are easily on par with BM hunts for solo leveling and with mana tap+life drain combo, there's almost never any mana issues. Shadow priests have dispersion, shadowfiend and mana restore on mind blast casts. If you're leveling a druid and have mana issues, you're doing something wrong. Imo, best way is to level as feral, though balance can also be quite fun to level with (not as easy as feral). Ele shamans thunderstorm, mana totem, mana shield... I personally prefer leveling as enha with a shaman; great burst, insta heals, lots of def and mana CDs. Also close to zero downtime due to mana problems.