Normally it's a deep clean everywhere that is going to be touched by decorations - so all the communal areas and my children's bedrooms. However, this year, like PickAChew, we're packing to move (slightly more notice than you, though). So added to the normal cleaning/sorting, we are doing a dramatic deep clutter, which will culminate in the horror that is our storage unit.
We've been renting a unit for the whole time we've been in the current country, as we moved from a big house to a smallish flat. I'm determined that we're not carting anything unnecessary to the next country, so it really needs a sort. Trouble is, we get to the unit, take one look at it and lose the will to live, quite frankly. Just the sight of floor-to-ceiling boxes of unknown crap makes me whimper. I'm determined though, and am bribing myself with Christmas decs. I'm not allowing myself to go to the unit for the decs unless I also plan to sort while I'm there.