I had been gardening for over 30 years before the daylily addiction hit so my gardens have many perennials in them. I do have a couple of beds that just have daylilies in them but I agree that it can get boring and look pretty bland once all the daylilies are through blooming. I like to mix some of the daylilies into my other mixed gardens. I find that grasses especially make a nice back drop for the flowers, especially the daylilies
In this garden I have shasta daisy, pholx, lots of lilium, peonies, hardy geranium, cone flower, feverfew (which self seeds everywhere) and Campanula persicifolia. As with many gardens I find that white is the great unifier
If I was to do this garden over I would make sure that I had a few more later blooming perennials in it.
This garden has many daylilies in it but it also had a huge clump of varigated Miscanthus grass and there are also quite a few peonies and lilium in this garden. Since the peonies bloom before the daylilies their beautiful blooms don't compete with each other.
You can see in this pic how the shasta daisies compliment the daylilies.
The grass really makes a nice backdrop for the daylilies. The peony leaves add texture to the garden and help to add contrast to the garden even when nothing is blooming. The daylily in this pic is LONG STOCKING.