I am always looking for interesting annuals to fill in my borders. Perilla Magilla (a relative of coleus) can be grown in full sun to part shade and has become a staple each year in the narrow area of my garden border. It does not have showy flowers, but it has beautiful magenta colored leaves similar to coleus. In my garden it grows close to three feet tall and about two feet wide. It looks wonderful next to David Phlox and blends in with pinks and blues.
Another annual that blends in beautifully with perennials in the border is Coleus 'Inky Fingers.' It is a weaver, trailing up to eight feet. Inky Fingers is described as mounding, but mine always sends out shoots on each side about four feet in length. It looks great with other brighter coleus plants, oranges, light greens, yellows. I plant it in the raised bed where I have boxwood bordering my patio.