The only spoiler to the retreat I will post right now is one of the books I used to help me prepare: A Coming Christ in Advent by Raymond E. Brown. Brown is a renowned biblical scholar and I used some of his academic sources in grad school. While A Coming Christ is based on his 750 page study of the Infancy Narrative of the Gospels of Matthew and Luke, it is written as a reflection on the Gospels to prepare for Advent.
If you are looking for a way to enter more meaningfully into Advent this year, I highly recommend Brown's book.
And, in case I don't get another post up before Thanksgiving...I pray you have a wonderful Thanksgiving and can count many, many blessings.