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.
While screens and boundaries enclose space, they also create barriers that restrict movement and views. Opening them up with doorways, gates and windows allows access or visual links to other parts of the garden, while also increasing visual appeal.