Oh Stir Fry! You have nice open space to plant some real beauties. The Rosy and Purple rebloomers are nice, but you can opt for something less common for some real WOW!

There are so many growers of daylilies who would welcome your "project" and give you some great ideas.

By way of another suggestion, I would ask them to send you a minimum of three double fans of each variety you select. That way you will have "clumps" much sooner. Plant them in a triangle giving adequate space for their roots which can be just touching, but not cramped.

Where you want spacing is between your clumps, and you have that available. Your Stellas will be small even when mature, so you might want to consider moving them to the front edge with taller varieties behind them.

Tell us some more about sunlight/shade conditions. Which way does the bed face?

Graham Stuart Thomas always recommended that plants with very good foliage be planted behind daylilies, since foliage is often their weak point. He liked grasses, but there must be others that would work as well. I think veronicas and echinaceas look nice, though admittedly, I am thinking about the flowers of these, not the foliage.

Thanks.
They are actually quite close to the edge (the walkway) -- the picture is distorted because I was bent down.

They get full morning sun until about 2:00pm.

Monarda's suggestion with Echinacea is a good one. I've also combined some of the fuzzy leaved new Rudebekias, I think they are called Cherokee Sunset. They are amazing.

How close to the daylilies would I put the coneflower?

Stir Fry, that really depends on the look you want. Noticed that you use part of the area to store the garden hose neatly. So that indicates that you need a path into the garden to get to the hose and to lead it out. Echinacea is taller and more narrow than daylilies until after the first cutting of blooms. The finishing blooms sit shorter and then the plants begin to lean out. Mine are between tetraploid clumps which are generally larger than diploids, and considerably larger than Stella. The clumps are 3 and 4' apart, with Echinacea and other perinneals staggered between them. Mine gets morning dappled shade, noon and early afternoon sun, with deep afternoon shade. So we have slightly different growing conditions. Hope that helps.

There's as many ideas as there are flowers! Just depends on what you like.