The WHPS tour of Jeannette Golden's garden last month offered myriad ideas for plant pairings, including great use of Clematis. Jeannette and I both garden under black walnut trees. They dominate her shade garden (first two photos below), so I took particular note of what does well under her trees.
Though, I must admit, much of the color and drama was in Jeannette's sunnier gardens. I realize my garden tends to concentrate on perennials and woodies. I rarely add annuals or tropicals, but it is those additions that really raise Jeannette's plant combinations to another level. They offer unusual colors and dramatic foliage that can be hard to achieve otherwise.