Leveling, HELP!

Hello, new multiboxer here.
Currently trying to level chars on Icecrown.
I am looking to hear what are the best methods of doing it, preferably for Horde.

Currently, my method is as such (boosting with a lvl80 druid):
0-9 - Just kill mobs
9 - 16 - Rage Fire Chasm
16 - 26 - Waling Caverns
26 - 40 - Scarlet Monastery
40 - 48 - Zul'farrak
48 - 58 - Black Rock Depths
58 - 68 - Hellfire Ramparts
68 - ?? Haven't leveled past this.

After 68 I've heard there are 2 methods. Either you gather all your tunes in a raid group and just farm mobs, apparently 1lvl = 1hour.
OR
You do quests, which also takes quite a long time.

Currently, I doubt I can optimize anything up to 68, but I need some help on how to fast lvl from 68 and further.
Anyone got any ideas/tips?

I used an 80 Ret, and boosted 4 at a time.....to get my 25 druids.

Only real difference is I didnt go to Zul'farrak. I did SM till 45 and then to BRD till 62 or 63.

Then I went to Sethekk Halls(and its quests) till 65, then Shadow Labs till 71 or 72.

Quested the rest of the way till 80.

I suggest Hellfire Rempart at 55 until 65, then move to Steamvault until 79. With a decent geared beartank, 74-79 take less than 1h per level here. At 79 doing 5 WG weekly give half of a level. At this point (you are naked ;p) you can do 5-7 quests in northrend or wathever to do the last half level to 80