I would definitely stick with hardy shrubs like boxwoods and other spruce varieties. You could create a bed using river rock as oppose to mulching. Knock out roses are hardy and bloom from spring to fall. The trick will also be to create height which can be achieved with Pencil Holly. Barberry shrubs will give you color and sustainability. Consider PomPom spruce shrubs as well to give your yard some character. You simply must get some Crape Myrtles but also choose trees that give great color in the fall.