You might plant a Redbud tree (Cercis canadensis) if there is a spot that is somewhat sheltered from wind. A gorgeous small tree/large shrub for part shade is Serviceberry (Amelanchier arborea). Shrubs for your shady northern exposure include Hydrangea, Japanese Kerria (K. japonica), Hypericum, Mahonia, Holly (Ilex species), Yew (Taxus species), Rhododendron, Korean Spice Viburnum (V. carlesii) and several other Viburnums. Pump up the color with sizeable drifts of perennials like Astilbe, Ligularia, Corydalis, Brunnera, and Hosta. (This is a tiny list of the possibilities!) You can dabble with our Plant Encyclopedia on BHG.com. It has a plant finder that lets you choose the criteria--shade, part shade, hardiness zone, color, size, etc.