There are many, but it would be easier if you can find a reference that gives you list or chart so you can sort by height, flowering or not, growth habit , exposure etc There are just too many choices without knowing more about your requirements.

How much space do you have? What's the soil like? What's the exposure?

There aren't a lot of conifers that love part shade but would you consider one/some.?

Don't forget a well placed inanimate object, like a large weather proof urn can take the place of a plant. A shot of shiny , hard surfaced color is a great foil to leafy greens.

I'd be happy to offer ideas once you give a few more specifics about the site.

Leucathoe, Mountain Laurel/Kalmia for evergreens.

I also like the Viburnums, but they will be more floriferous and have better autumn color in more sun, like the Fotthergilas, though they don't need full sun.

For the dogwood, do a cluster of three. They really stand out against a light backdrop, be it the siding of a house or snow. Or you could use them against a dark green backdrop of rhododendron. Just give them a relatively solid, contrasting backdrop rather than miscellaneous twigginess. One of the nicest uses I've seen was in front of a grove of aspen, with the red twigs highlighting the light bark of the aspen trunks.

I personally love bleeding hearts.

Compact and showy, yet delicate, and those poor things can really take neglect (say for example, you forget about it over winter and let it freeze inside its pot hahah).

Also very easy to propagate :)

Kali C brings up a good point. While the standard bleeding hearts are perennial/nonwoody, they can be small shrub sized, and there are other perennials that during the growing season can reach medium to large shrub sized. I am thinking in particular of the gold Aralia Sun King, which can get over 6' in a single season, though since it is perennial, dies back to the ground in cold weather. Do you need or want a year round presence in all of these places, or is a large perennial OK for some of these spots? I think that A. Sun King might be more effective than Ogon Spiraea in more shade. Both are gold but with quite different textures.

Thanks to all. As for placement, I have several places, ranging from part sun to part shade to full shade, but I'm not looking at any deep shade areas right now. Some of my full shade areas are along the driveway and behave as a woodland edge, but the trees on the other side of the area make it dappled sun most of the day so it is shady. But, having some under canopy things right along that edge would be beautiful.

Before this year shade=hosta. This summer the world of shade opened up and I'm so excited about all the options. I think I've also become very content with the "un-catalogue" appearance of plants. Before, the lusher and more prolific a plant/tree bloomed the better. Now I'm really seeing beauty in a tree that has more "zen" to it--branches reaching towards the light with fewer blooms, but with a beauty in the sparseness that adds shape, color, and variety to shadier areas. Add to that woodland edge plants here and there, like all those wonderful asters along the roadsides, and it gets even better.

NH Babs, I have four Aralia 'Sun Kings' that I planted in August in strategic areas. I'm hoping that the way I've placed them creates both repetition and bright color. Can't wait for next year to see how they do! I'll be reporting on how tall they get given thymetodig's experiences in NH. One of mine is in full shade all day, meaning I don't think the sun hits it directly although it does good dappled shade. The other three are opposite each other with different sun exposure, so a comparison of those three will be enlightening.

I'll respond more fully to all the suggestions later. Extremely busy couple of weeks right now!