the absolute fastest way to level is with RAF and questing. just avoid the collection quests where you need >5 or 6 items per guy. kill quests are your friend.
check wowhead for quests that reward gear and you'll save loads of cash

by the time you are in your 40s, your turn-ins will be giving you 30-40k xp

while 5 boxing without professions, and not being too gungho about it, i was able to hit 60 with a /played of about 4 days (i've heard as low as 2 days). 5-6 days with professions (i'm also addicted to the AH)