My characters are from Horde

I have 4 leveling accounts (2 main, 2 RAF), level normally till lvl 8 (takes abt 1hr max)
Use my 3rd main account character who is a lvl 80 Prot warrior, run thru the 4 leveling chars on the following instance:

get RFC dungeon quest just outside RFC
lvl 8-16: RFC

get SFK dungeon quest at Silverpine Forest
lvl 16-22: SFK (park them at the fence just infront of the portal, and run my 80 warr, aggro all mobs till the boss, Razorclaw the Butcher, and finish them off on the other side of the fence where my lowbie stand)

lvl 22-40: SM-Cath (3 positions to park them, 1st at the starting passageway just before the open park, 2nd at the central fountain on the higher ground, 3rd outside the door of catheral)


get ZF dungeon quest at Gadgetzan
lvl 40-48: ZF (mount up, and aggro mobs till the furthest Gahz'rilla pool area, and run back to the 1st passageway where 2 long stretch of walls is, Stay LOS to gather the casters on you, and AOE them.
When running back to the AOE location, you have to park ur lowbie behind the 1st stone where the 1st group of mobs stand. this is to prevent aggro when your 80s is Hexed and yet get XP)

lvl 48-60: Stratholme (Zone from Undead portal, Clear the Life side till the 1st gate nearest to Life portal, this is to be prepared for your lowbie death and who will zone in from the Life Side. Sucide all your lowbies if no rezzer is left in the group, use your 80s to aggro the rest of live side from the 1st gate last clear to where the lowbie zone in in Life side.
It is a little tricky on postioning the lowbie as pats will respawn. clear till Baron Rivendare, hopefully, Deathcharger's Reins drop

Park your lvl 1 alts who will summon-a-friend at major cities and instance door, this can save lot of time running from instance to instance.
you will have lots of break time after 5-6 instance reset per hr, so get some fresh air
It took me 17-20hrs to level 4 characters from 1-60. Hope you can break my record