I have to say MoP is the easiest one to level an alt on, at least since they changed the XP requirement. I got 5 alts from 80-90 in 2 weeks, only playing 2-3 hours a day. On my DK which I spent the most time after 90 on, took 2 days to get to 480 ilvl. Not sure if I am just lucky or what but it seems very easy to level and gear an alt now, and dailies really aren't needed on an alt imo.
As far as what I think didn't work, number 1 is the lack of dungeons, while I do enjoy heroic scenarios, I think it was very lazy for Blizzard to stop designing new 5 man content. Raid Finder is a very unpleasant experience and should not be the primary gear up method.