I have a hard time decorating with the boys at the age they are. They are into everything! I admire the people who can put up a tree every year and manage to keep their very small children from knocking it down or eating ornaments (or the tree). These are a few of my kid friendly decorating ideas.
Throw a square of Christmas cloth over a table. If they take it off, just put it back on.
Hang seasonal items on the wall, high above their reach.
Hang decorations on knobs in your kitchen or other areas of your house. This one is in our laundry room.
Wrap an existing picture to look like a package. This is my favorite idea which was gleaned from McDonalds.
I also have a Christmas runner on my dining room table which I forgot to take a picture of. The boys have been using it as "a road" for their dump trucks. My nativity is on top of the entertainment center and there will be pictures of that to come.