"Whew, am I glad to have avoided that!"
Sometimes it's not about what you accomplish in Azeroth -- it's what you successfully avoid. It's the relief that washes over you when you realize the tank successfully held up during the ugliest phase of the encounter and you didn't have to charge in with your untried new tank to ostensibly save the day. It's the realization that you haven't been vote-kicked from a pickup group in months now (whether you deserved it or not). It's chugging right along into the next raid on a roll that's seen the guild free from loot drama since ... oh, I don't know, Firelands?
Whether it's a personal failing, content you detest, nasty social drama, or some other unsavory happenstance, what are you most pleased to have successfully dodged in WoW?