Miscanthus comes in several heights; the pink plumes are quite attractive in late summer. Sedum, such as Autumn Joy or Neon, will do fine if you give them a good slope. Plant lots of bulbs, especially those in the allium family. A shrub, but carefree, is callicarpa(Beautyberry). Low-height interest/borders can be provided by using bearberry or lingonberry. The newer varieties of Rudbeckia have a very long blooming season; they will love the sun but also like a bit of slope to prevent water standing. Interplant a long-blooming mildew-resistant phlox such as Katherine with amsonia (blue spring flowers and bright gold fall color). Katherine is only about 30" but David is quite tall; carolina phlox gives a different feel and is well-behaved. Don't forget to provide winter interest, there are several blue-toned and golden 'evergreens' in differing sizes and shapes, which will be nice when every thing else is hibernating. West-facing will be awfully hot in the summer, you might want to consider planting a sumbucus to one side, to shade the house.

Get on the mailing list for several catalogs and see what appeals to you!