Instead of having the "newbie experience" for boosted 90s in the expansion only available after determining your boost, it should be the basic newbie intro. Pick a class, get set to 90, get sent to Noob Prison Island with no way off, play around, see if you like it, at the end of the quest chain you get your ass booted back down to level 10 (You quested in the tutorial, whatever, here's the your ability to pick specs) unless you pay your Blizzard Bucks. Didn't like the class? Pick another one and give it a ride. Don't have to apply the boost until you're done with the newbie/tutorial quest chain.