Like a little black dress, some plants are classics and never go out of style. This fall as things go dormant look for bare, boring or difficult spots in your garden, and next spring invest in some classic plants that you don't already own. For example, all well-dressed gardens need astilbe to light up shady areas with their deer- and rabbit-resistant, ferny foliage and lovely flower spires.
Bleeding heart is another classic for shade, although the plants die down after their spectacular flowering of white or pink in late spring.
Digitalis (foxglove) is also deer- and rabbit-resistant and blooms in shade in early summer, making a striking vertical statement.
In sunny spots, the Shasta daisy ‘Becky' has great substance, so it never flops over and is pest-free and provides lots of cut flowers all summer (if dead headed).
The same is true about nepeta (catmint) ‘Walkers Low' that looks like lavender in the garden but is so much easier to grow. I use it in bouquets, and then when it starts to look bedraggled, I just shear the whole plant off quite low and it rebounds and re-blooms!
Salvia ‘May Night' also repeats if dead headed and provides that wonderful dark violet-blue color that looks wonderful with any colorful blooming neighbor.