I envy you! Of course you have mostly spring flowering shrubs. You need summer color. You could add daylilies which will flower in the summer. They aren't just yellow anymore. There are some very colorful varieties.

Also, lantana is a very nice easy to grow perennial that should come back in your area. It's also drought tolerant so you don't need about watering.

I spoke to my neighbor who grew up in my house and she told me that the conifers in my yard are cunninghamia trees.

what about calla lillys ? those are nice and they do very well here in the south .

If it is shady you might consider bushes to fill your holes like nandina (colorful leaves) or mahonia (large, spiky dark green leaves with yellow flowers in Feb. and purple berries in the summer) or itea (flowing white panicles of bloom in spring) or hydrangeas for summer bloom. Maybe some sweetshrub or gardenia?

Perennials for shade like hostas, ferns, lenten roses and liriope look great bordering azalea and camellia beds.