When I first began planting them in The Garden at Winterhaven my only criterion for planting a perennial was its flowers. Over the years I've become more picky, and prefer what I think of as low-care perennials.
I no longer plant many things that have to be divided often and in fact prefer plants that never need to be divided. And I look for plants that don't require a lot of water or fertilizer. That doesn't mean I don't indulge in a few fussy ladies but I try to limit myself to just a few plus of course the roses who are not low-care either.
All the fussy ladies live together in one bed where I can provide them with the water, attention and nutrients they demand.
The rest of the collection grow in burms and beds all over the garden where most of them thrive and few struggle and get weeded out or slowly disappear when they just don't cut the mustard.