For a brilliant splash of purple, consider 'Sugar Plum' Coral Bells (Heuchera). I have it edging a long border with bluebells and a white evergreen candytuft plant ( don't know name). They soon reproduce themselves too, so are good value.
Border columns made with wood post placed in flower beds close the walk are beautiful, add lots of interest to the garden Place a big container of pretty flowers on top of the post. maybe could use pvc pipes w flower basket set on top?
Peony and Iris border: Neighbors down the street have an old stone wall out by the road. A border of pink peonies and various shades of purple and lilac irises grows in front of it. What a glorious sight it is each year.