Daylilies, while gorgeous in bloom, are somewhat less exciting when only in foliage, and may leave a total void when dormant. Mixed plantings are the answer for an overall attractive display garden.
Your need is to showcase daylilies, so your design will be daylily-heavy instead of a balanced ornamental display, but you do need to include some other things. You want the eye to slow down and actually look at the individual plants and see how the plants play off against each other. A field of all one type of plant can be "taken in" in a sweeping glance, and won't encourage further exploration.
Along your 80 foot span, use large drifts of daylilies interspersed with a few other perennials. In front, try evergreen perennials such as mat-forming 'Bath's Pink' dianthus, iberis sempervirens, phlox subulata, or shorter sedums such as 'Blue Spruce' or 'Angelina'. Pick one of two types and use them repeatedly along the bed as a foil to the daylilies. Steer clear of some of the neon-pink flowered dianthus, as they may clash with the daylily colors.
Behind the daylilies, use your 2 'Pinky Winky' hydrangeas, about a third of the way from each end of the bed. Allow enough room for their eventual size. You can limb them up slightly to maximize space below them. Mid-way between the hydrangeas, pulled forward in the bed, would be a good spot for the fountain.
The wisteria might work on a VERY sturdy pergola, athough likely wouldn't be in bloom at the same time as your daylilies. Another choice would be a climbing rose and/or clematis or a native honeysuckle (lonicera sempervirens). 'John Clayton' is a yellow honeysuckle that would mesh well with typical daylily colors.
