Well, you've given me hope that one day my mondo grass will get the message and start to spread!!

FWIW - Liriope is a polite clumper for me and takes ages to become even mildly jolly - let alone boisterous. And the variegated one is slower again. But the Hemerocallis tend to take off hugely.

If you are using varieties with similar growth rates and leaf heights then the Liriope will be a lovely foil and give interest in the no flowers time. I'd be thinking that the taller varieties of daylily could tend to become boss in the garden patch.

With a wide bed, and the daylilies set back from the Liriope this may not ever be a problem, however.