I've leveled three toons through outland, and two through northrend (all solo) using Jame's guide as an addon (tourguide format) and they're great. They tell you exactly where to go, what to do, etc.

I'm currently using Jame's horde guide to get up to 60 with non-RAF bonus on my prot pally/holy priest duo and they're doing well. Every EXP check in the guide I'm usually just a few bubbles off, some of them I've done a bit of grinding to catch up, others I just said "meh" and continued on and was still appropriate level for the next part of the guide.

Jame's Guides rock, IMHO, and especially since you can get them in TourGuide addon format and if you also use Carbonite, Carbonite ties directly to tourguide and provides an onscreen arrow of your destination, ETA to get there at your current speed, and the Carbonite minimap is invaluable for showing what areas of the map you need to go to for each quest, whether its a broad area that the mobs spawn in or the specific location of a stationery object or mob.


So, if in Azeroth I can manage to keep up with the guide on a non-RAF group, it should be fine in outland as well, especially given the reduced exp requirements from 60-70, and also given the fact that while boxing, I can do almost all the group quests solo without breaking a sweat.