One Hydrangea I'd like to try is Hydrangea p. 'Vanilla Strawberry' which has 10" flowers that open white, then after two weeks turn blush pink and then a dark rose color. As it flowers continually for weeks it has a tri-color appearance in bloom and the cut flowers last for over 12 days in water.
Next on my want list for sunny borders are some of the newer Buddleias. 'Ellen's Blue' is a compact 4' shrub that is disease free and has beautiful blue-violet flowers and silver foliage. Other Buddleias that look worth trying were those in the Flutterby series -- they come in lavender, pink and vanilla and remain low and compact, a great advantage as even though I hack my butterfly bushes to the ground every spring, by the end of the summer they are always tall and gangly.
I'm also tempted to plant Caryopteris 'Grand Bleu' which is meant to be the deepest blue caryopteris. It's a shrub I really appreciate in late summer when most other plants have passed their prime.
Some recent plant introductions I have little interest in -- a re-blooming lilac, Syringa 'Bloomerang' looks to bear flowers less vibrant and fragrant than it's once-blooming relatives. Why plant lilacs unless you can fill a room with their scent? The zone 5 hardy crape-myrtles, Lagerstroemia 'Red Filli' and 'Violet Filli', also left me cold; small droopy things with none of the wonderful bark that I value.
Of the sun perennials I am particularly enamored with the Orienpet Lilies -- 'Alchemy', 'Scheherazade' and 'Silk Road' bred by Judith Freeman of The Lily Garden. They combine "the sublime beauty of Oriental lilies with the garden persistence, heat tolerance and color of Trumpet and Aurelian hybrids."
Coreopsis "Star Cluster" looks pretty -- white with a burgundy eye at the base of each petal. It is one of the coreopsis 'Big Bang' series, the product of 10 years of intensive breeding involving up to 8 different Coreopsis species. All in the series are meant to re-bloom without deadheading, be cold hardy, and have large flowers in a wide range of colors and patterns.
Sedums are back in force, many looked wonderful and are one of the few things I manage not to kill in summer containers. This year I plan to plant even less annual containers and rely more on sedum plantings that can thrive for weeks without water.
I planted Alstroemeria 'Laura' when we first moved to PA, it still thrives in the shade. There are some newer Alstroemerias 'Inca Exotica' and 'Inca Ice' that flourish in our zone and make great cut flowers. I'd like to order both for my perennial gardens.
Of course there were echinaceas by the dozen, in different colors and petal formations, doubles, singles, quills. Still can't understand the fascination with pompom echinaceas, they just look rather silly. And although the new yellow and quilled Leucanthemums were pretty I don't really want to give up garden space to something that only flowers for a couple of weeks and looks ratty for most of the year.
I haven't had much luck with Heuchera's, many people's favorite shade perennials, but I am intrigued by Heucherella 'Redstone Falls' and 'Yellowstone Falls' which have a trailing habit and put out strawberry like runners that root along the nodes. They could be invaluable in the shade garden, and provide a carpet of foliage color for months.
I covet many of the new Hellebore cultivars -- the new Winter Thriller series look wonderful, 'Red Racer' had 3" red flowers, 'Night Coaster' was a dark satin black and would be fabulous against a dusting of snow.