I have some 'pie shaped' beds, and I have planted them with the tall cultivars along the back, having the cultivars graduate down to the shorted ones on the points. Mid sized ones in the middle of the bed. With short ones, especially ones with smaller blooms along the front row. I hope this makes sense
I will also try to arrange colour, with the softest colours blending to more dramatic colours. Also, you can pick an eyezone and put a cultivar a similar colour to the eyezone of its neighbour. Just as an example, I would place a cream or blush coloured short cultivar on one of the points, then next to it a slightly darker cultivar, say a slightly darker pink, then next to that a pink with a darker eyezone, then the next would be a daylily the colour of the eyezone.
I am sure other people will have suggestions, as well!