This is my border in August. You can see some of the different colours of perennial phlox here. What I love about them, is that they don't all bloom at exactly the same time - so I have a lovely array of colour from mid-July right into September.
The 'Michaelmas Daisies' or fall asters put on a great showing in the later summer as well. I started out with just two of them in 2008 and have divided them twice already. Love them. Couldn't resist posting this picture of Hudson posing in front of them.
This clump of fall Monkhead (I'm not sure the exact variety, as they were a gift from Rita) bloom much later than my other ones. They have a tougher and sturdier stalk, but otherwise look very similar.
And one of my very favourite later blooming plants is my white coneflower.