Does a double album count as two?

Counts as one as long as it's not a compilation album. For instance, "The Wall" is a single work that happens to span two discs.

Jethro Tull: Thick As A Brick
- A somewhat unusual choice, but then again...

Damn, I knew I'd left something important off of my list. This is not an unusual choice at all, I would expect it to be on many people's lists. One of the true all-time classics.