Okay. Never mind! :)

Heliopsis helianthoides "Summer Sun" is probably the longest blooming plant i have. I have some salvias that bloom almost as long, but they are not yellow
or daisy-shaped. I dead head the first flush of blooms in June, and it will continue to bloom (with smaller flowers) into september. So maybe you have made a good choice with heliopsis "crown jewels."

ever tried the narrow leaf zinnias, zinnia angustifolia?
they bloom all summer and reseed in my beds. flowers are small (about 1") and color choices are white, orange and what they call yellow (looks orange against a yellow marigold but appears more yellow next to bright orange flowers).
they grow in a loose mound to about 15" or so. i have cut them for a short vase but the stems will be about 6" or less.
there is also the "profusion series" of hybrids of these that expand the color range and the plants have slightly larger flowers.
helianthus angustifolia, or swamp sunflower, doesn't bloom until late summer but are very showy, covered in bright yellow flowers. this one can be a vigorous spreader in moist sites but is a good plant for the back of the border to about 6' tall.

If I keep deadheading my gaillardia blooms all summer.