Ours generally go up just before Christmas, sometimes on Christmas Eve, and are down again by Twelfth Night.
I love them when they all go up but, although we only have everything out for a relatively short time, I am so glad when they are all away. 
Nowadays, when we go away for Christmas we don't bother to put any decorations up beyond the cards - so much easier!
Years ago, when DC were small, I remember a house in the next road to us where the decorations remained up all year round! The house looked very uncared for and the decorations certainly added that 'certain something'! 