My favorite room! It's to the left rear of the main lobby, past the reception desks. Walk in, go all the way to the stairs that go down to the outside, turn 90 degrees left. There's a little DVC kiosk/desk in front of it.
It's a great chill out/reading room, has a balcony overlooking the side wildlife area, and at certain parts of the day is used for lectures/classes/talks, etc.