Yeah, I've taken short breaks from FFXI to play WoW in the past. It is a good game in my opinion, but for me it still lacked something that FFXI has (and generally I missed all my friends on FFXI).
I'm starting to get to a point in FFXI, where I can't attend as many end-game activities due to getting / trying to get a job and being in a whole different time zone to Americans, and a lot of shells don't like that. I'm just lucky my current shell can put up with me being late or not showing up.
But anyway, it's good, so enjoy it. ^^
Edit: BTW. Even though I could generally play FFXI 8+ hours in one day, I still found it slow to level in WoW. Not as slow as FFXI, but slow enough to notice.