I have been doing the bare minimum to get me to the first boss in the zone's instance, then I twist on that until I can kill the 2nd boss, rinse repeat until I level out of the instance. The instances are great xp -- I've been getting at least a level every time I go in, even if I stop at boss 1. I stop when running the instance only gets me half a level or so.

Then again, I'm not particularly flying along...