I can't tell, do the plants go all the way to the fence? How about trellising something over the fence? Or adding some height behind the left bed. Say, scarlet runner over a tripod trellis? You have a nice lush burst of color going :)

Wow!
I love your garden.
Why would you want to change anything?

I think it needs 'bones'. Evergreens. Structure. Privacy.
Why limit yourself to perennials?

Your garden looks beautiful. But if you want a change, what about a skinny tree, or even a pampas grass.