I took a cookie class from Sharon a long, long time ago and this is my go to recipe for Icing. Make it ahead and store in a sealed container and you will be ready for anything!  I even make my sugar cookies up ahead and keep them in the freezer and then when the kids get home, we can just pull them out and add a little food coloring to the icing or just dump decorator sugars in a bowl and go to work making a treat together.  Memories are just waiting to be made.