I like to plant lots of annual coleus with my flowers.
I love coleus, (don't we all), for their showy colorful leaves and their wonderful way of rooting in water. Once their little white roots appear on a stem it is easy to pot them up or stick them into the garden, and magically one has new plants. Water the plants well for a time after they are planted in the soil.
At the moment, I am enchanted, (of course, you will recognize that I enchant easily when it comes to plants), by the dark red coleus that glow when the light catches them. I cut them to use as filler in bouquets, and they absolutely enhance every flower that they are combined with. My friends are tired of my admonitions "to remember root the coleus" in the bouquets that I give to them!
There are so many colors and color combinations in the leaves that coleus plants present. The chartreuse and brown and russet and orange shades provide such a deep burst of color in a bed or in pots or borders as they enhance each other as well as the flowering plants. They make splendid pops of color, too, even in a plain, old all-green bed of groundcover.