I always have cosmos, I really like the airiness of the foliage as well as the colors.
Snapdragons, I really like the tall "Rocket" series are prized for their early flowers.
I also normally grow portulaca. They have such bright colors. A favorite is Sundial fuchsia. They sometime successfully reseed for me.
I grow a variety of marigolds. Some of the oranges are so intense, they almost hurt your eyes.