It's always tempting to plant a lot of spring bloomers. But once they've finished being spectacular, it's then what?
I have no idea if any of these native perennials would work with your design, but they're usually reliable and many will bloom from now through fall.
There are many salvias/sages that I bet you could grow. For example, here's a recent picture of my Salvia Greggii (Autumn Sage). It will bloom all summer and into fall
There are so many salvias in various colors. Reds, hot pinks, light blue, dark blue, white, etc. You can always flip through our database that's specific to them.
A year or maybe 2 ago I planted some fall asters. I 'think' they don't get terribly huge. Mine are already greening up but I'm thinking they won't bloom now. Here's their first year bloom.
And greening up now. Think maybe they're planted too close together. Will wait and see.
Can think of many more but have to get off the computer!