The 'Red Robin' is a type of Photinia plant, an evergreen shrub that will sit in any border.
Next to mine i have a buddliea, a clematis growing through it and a rose and another clematis behind it.
Directly next to it i grow another Photinia called 'Pink Marble' which has variegated cream and pink leaves.
Under it i have a geranium, heucheras, pachysandra and aquilegias ..... there are many perennials and small shrubs that would be happy under your plant though.
By looking through folks pictures and blogs you'll see a lot of inspiration :-)