Not that long, apparently. I got my Shaman up (as mentioned elsewhere) - mainly to help my wife with her Less-Rabi achievement. I did waste a little time playing around with leatherworking - those basilisks in Zangarmarsh cost me easily an hour of my playtime.
And I have to say.. I enjoy leveling now and then. There is something wonderfully satisfying about learning a new ability/spell. Preferrably truly new - not Fireball (Rank 124322).
The leveling game seems to be weirdly limited, though. I mean.. it accounts for only a tiny tiny amount of the total game.
I suppose running after achievements and doing raids takes a bit longer after all.