Herbs are tough to highlight in the evening, but the idea of placing single candles in small terra cotta pots in front of them is charming...and effective. I know I have pinned this before, but it's definitely worth another pin.
Sometimes using just one plant gives the drama and impact that you need. I don;t like many containers that are too busy and are just a hodge podge of color. The same with flower gardens. I like a theme that flows through the garden. It takes restraint in planning but looks by far the best, in my opinion!