As I grow older I grow more and more annuals. I know this distresses many of my rock gardening friends...but that's too bad. I think that many annuals proffer colors and qualities that aren't matched by perennials. Some self sow and maintain themselves as reliably as perennials.
One that has impressed me enormously this spring is Roemeria refracta, a tiny poppy from the Mediterranean. It is only five or so inches tall and barely 8 inches across. It has been blooming for the better part of two months and shows no sign of stopping. It has multiplied tremendously since I first obtained it a few years ago, and is small enough and delicate enough that it doesn't seem to negatively impact its neighbors. I shall encourage it to spread more widely in my dry garden.