I was particularly struck by one blogger's list of what did and didn't work for her in dry conditions. Here's what does well:
Shrubs: aucuba, nandina, Heleri holly, junipers, spirea, euonymous 'Emerald Gaity', weigela, bottlebrush buckeye, Meidiland rose 'Alba', and oakleaf hydrangea (in full shade).
Perennials: hosta, sedum, Russian sage, daylilies, ornamental grasses, liriope, carex, solomon's seal, garden phlox, euphorbia amygdaloides, purple coneflower, aster, black-eyed susan.
Then she rants about rhododendrons, which I am coming to agree with, and astilbes, which I love but that sit there gritting their teeth and shriveling up in high summer. As a Maryland gardener says, "And the biggest wuss, in my experience, is astilbe. They do nothing for me in summer except threaten to die."