Do you have a few high-maintenance people in your life? You probably don't mind too much, as long as they offer some sort of trade-off (high energy, creativity, etc.). It's also important that there be only a few of them, otherwise you'd be experiencing some serious overloading, right?
Plants are a bit like people in that regard. It's OK to have a few plants in the landscape that are fussy and demand a lot of attention (assuming they have good qualities that make all that fussing worthwhile), but having too many plants that are difficult to grow means excessive work. And I don't know about you, but some days I want to just lounge around in the yard and admire my perennials, rather than caring for them.
Enter ten perennials that are easy to grow, as described in this article by Marie Iannotti. About.com's Gardening Guide touts these ten plants as being examples of perennials that "allow you time to enjoy gardening." Included in Marie's list of perennials that are easy to grow are:

Comments
Most perenials are easy to grow, make sure they are planted in proper place and right soil. I have never lost any perenials. With trees or shrubs it is different story.
Most perennials hardy to our zone are easy to grow. But maintaining them in terms of removing/cleaning up last years die-back of stems exists every spring. But with roses, it is a whole different story. In my opinion they are the best, beautiful & floriferous perennials for any sunny garden. Give them a good start when planting. That’s about it. They are on their own.