I went to Outlands at 59, with like 4 bubbles to go. WPL was giving me so much exp, I didn't want to start wasting Outland quests and end up in Zangarmarsh at 60 or something.

Here's what I did:

1-8 Quests
9-16 RFC
17-22 SFK
23-40 SM
40-59 Quests (STV, Feralas, Tanaris, Ungoro, Winterspring, WPL)