That decision for me is sometimes quite easy, but sometimes also quite difficult. I love the natural time worn elegance and "life" marks most pieces present to me. Sometimes, however, a fresh look is in order. Take a look at the picture below. The wood trim on this room divider is dark and gets lost between the sweet toile panels. I debated. Facelift won.
And below is the after. The wood now frames the toile and brings out a lighter tone to the entire look of the room divider. The pictures really don't show how gorgeous this is (had to flash, sorry!)....and it looks SaWeet by my bistro set.