Here's a notable historical work for you. Just framed this beautiful European landscape by Louis Apol (Dutch, 1850-1936), "A Forest in Winter" (oil on canvas, 32 x 25). (Click image for a larger view.)
The stained quartersawn white oak frame is a 4-1/2" wide slope with a carved cushion sight edge. The double reeding outside the cushion, with carved stops near the corners are a nod to the delicate strokes that define the trees, and give the frame a degree of refinement in sympathy with the artist's well-honed touch. The 1/4" gilt slip catches the sunlight. We were aiming for a suitably rustic but sensitive feel, a quiet mood, simple. No "before" shot of this in a gold frame, but can you see how the dark wood suits the painting much better than a gold one would? How it's like the shadows in the painting, and how the shadowy feel of the frame leads your eye to the picture and acts as a foil to the picture, and in particular to the sunlight? And, of course, the rustic feel connects you to the rustic subject matter much more successfully than would a gold frame.
Below is a corner sample of the frame design (without the carved stops on the reeding).