I would think any almost any color bloom would go--good luck! Google *perennials for your zone* then choose which ones you like. You might try looking at the Perennial Forum here for some ideas also.

I have some paired with angelina sedum in my sunny front yard and it makes a beautiful groundcover. the chartreuse and blue look great together. Behind it are taller perennials (mix of purple, blue, and pink flowers), and a butterfly bush that has gray/silvery foliage to pick up the cool tones of the juniper.