Let your grass become the backdrop and texture holder. Add Achillea, Baptisia, Nepeta, Coreopsis, Delphinium and maybe some lower grasses like Deschampsia, Carex (grass relative), Schizachyrium scoparium The Blues or Blaze, and some groundcovers like Thyme (Spicy Orange would look great), Corsican Mint, and Delosperma. Remember, don't overcrowd, just add a few of what I suggested, or just one, and add just a couple of things to invite color, texture, and form.

I have a nice switchgrass blooming now. It is either "Hanse Hermes" or "Rostalbusch" (sorry if I butchered the names). Planted in front of it are pink petunias. Planted on one side and in the rear are A. Tuberosa (3 foot tall butterfly weed...in bloom). On the other side are 2 big amaranths (flowering in crimson and dull green).
I was just noticing yesterday how good these look together. Sometimes you get lucky.
My switchgrass is only about 3 feet tall. "Shenandoah" goes a little taller than that.

I have all sorts of 'Rotstrahlbusch' in my yard. I like the look of Sedum 'Autumn Joy' next to it. The colors look great in late summer/fall.

Thanks to all of you. I do like the look of butterfly weed in front of my switchgrass. I'll have to get some more seed for next year and plant further away from the grass. It sure got bigger than it did last year! I have to work on my spacing more.

Sally