heres what i've done with my RAF chars.
quest up to lvl 10.
use a nonlinked 70 to run you through instances. (im using an enhancement shaman)
wailing caverns until lvl 20.
sm library until 30. (<10 minutes per run, avg 75% of a lvl per run)
sm cathedral until 42. (10-12 minutes per run, avg 70% of a lvl per run)
zulfarrak until 53. (i skipped the stair event, the xp/time spent on it didnt seem worth it.)

im sitting at ~20 hours played at 53. im not entirely sure what i'm going to do til 60.
i tried a strat run last night but it was slow going, my shaman is only t4 geared and it took
some time to work out what i was doing. i'm going to try again tonight and see how it goes..

all in all this was so fast, im thinking of boosting a couple mages as well.