Breakfast Topic: Favourite instance

You've run it ten or twenty times and you're still not bored; the drops are good and you've mastered its mobs. Solo or in a group, what's your instance of choice, and what makes it so good?

The Deadmines would probably take the crown for me; despite being a low level instance, I managed to run through it first time with a seamless PuG, and now that I'm all grown up I revisit it for fun. On the flip side, The Stockades is probably one of the most boring instances I've done, but since it's the first time my druid got to tank an instance it holds a special place in my heart.