I leveled to 70 in Outland.
Did I go to Northrend then? Nope. It was the Isle of Quel’Danas.
Without a lot of time to dedicate to leveling, I did have the 30 minutes to do the dozen dailies on the Isle. It was very adventagous since the first run of the quest I was able to replace my quest bow with Valanos' Longbow.I took some time to talk to some Horde friends about Northrend. Stop highly recommended to me to take the zeppelin outside of Undercity to Vengeance Landing.
I was taunted with the thoughts of plague spreading and mass murder. *cough*
Howling Fjord has been a test bed for the Royal Apothecary Society since landing in Northrend. The tasks to be done there were vile and interesting. This gave a lot of depth to the quests I knew to come in Dragonblight.
Plus there are not spiders on the road out of town to eat your face. Amazingly this is a huge plus.