I'm finding that since the quest xp bonus and xp per level required reduction of the recent patch, some zones can be skipped entirely. For example, it's now possible to completely bypass STV without endless grinding to balance out the loss of xp in a zone. To encourage more people to buy the WotLK expansion, Bliz is making it incredibly easy to get to 70 to "require" the new content when it is released. I was following Jame's Alliance guide, but realized I was already level 33 (when before I'd start the guide at level 29), and skipped the Shimmering Flats (ton of collections) and STV quests, while still being 'ahead' of the guide. I suspect I'll end up skipping certain areas, such as the Swamp of Sorrows and most new Dustwallow Marsh quests as well, since I'll be so far ahead in level. For the 40's, I'll probably pass on Feralas.. and for the 50's.. Silithus.