Our tree and lights stay up through the twelve days of Christmas and come down after Epiphany (which celebrates the arrival of the Wise Men bearing gifts to the Christ Child), January 5th, I believe.
Advent consists of the weeks before Christmas when one is preparing for and anticipating the arrival of the baby Jesus.
We celebrate through Epiphany, too, and have an Epiphany Party to wrap things up. People are still wanting to celebrate and we all finally have the time available. We have to put a flyer in with our invitations, tho — a definition of Epiphany, for the non-liturgical and non-churched.
In Vienna, they start the Waltz Season December 26 and go til - what? Epiphany? Lent? In Merrye England, they celebrated the Twelve Days After. The Puritans left some of the good stuff behind, but it is ours for the taking.