Level 48 as alliance...

These are the zones I hit, when I quest to level.
I'd look at... Stranglethorn Vale (44-45), Tanaris (45-46), Feralas (46-47), Hinterlands (47-48), Feralas (48-49), Tanaris (49-50), Searing Gorge (50-51), Ungoro (51-53), Felwood (53-54), Tanaris (54-54), Ungoro (54-55)....

I mostly follow the Brian Kopp alliance guide for 1st to 70th level content.
I skip a lot of the collection quests, now that 1st to 70th only requires 70% of the experience per level that it used to require when that content was the current stuff.
And the 2 pieces of BoA +experience gear help a lot too.