Winterberry might work. Redbud is allegedly an understory tree. Tulip trees seem to germinate in shade around here and have beautiful flowers but they do get very tall and have brittle wood so not good for close to the house. Staghorn sumac is a thought but I'm less sure about that one. The amelanchier was actually my first suggestion. For winter interest witch hazel is good.

How about Japanese Stewartia, Stewartia pseudocamelia.
flowers in early summer, purple fall color, nice pyraidal habit, but the truly outstanding feature is its red flaking bark providing year round interst.

You asked for an evergreen. So how about American Holly, Ilex opaca?

I love Halesia carolina (tetraptera), silverbell. And what about the smoketree, Cotinus obovatus? Hemlocks would be good if you can keep the wooly adelgid out. I have a stewartia, which is a wonderful tree, but it got much larger than it was supposed to! The blooms are magnificent, and yes, the bark is lovely, too. Also, redbud is one of my favorites, but it seeds out so much that I would never recommend it near a house or urban yard. If you go with shrubs, there are several viburnams and rhododendrons that will perform in part shade.

My suggestions include American Holly - great for winter interest, and attractive all year 'round. In your yard probably will never reach 40 feet. but will become a small tree; Flowering dogwood - Cornus florida - great spring flowers, nice red foliage and berries through much of the fall. Not a large tree, grows to perhaps 30 feet. Not densely branched, rather open structure; Flowering crabapple - nice flowers, holds fruit through much of winter. not much fall color; Hawthorns - so-so flowers, but nice winter interest with colorful berries. I wouldn't worry about the smell of the flowers because, although it may not be a wonderful smell, I don't find it very strong.

My first suggestion would be amelanchier, but you already have that so some second choices, that I have in my shady yard include: witch hazel, redbud and pagoda dogwood.

If your after more winter interest, you may want to look at Harry Lauder's walking stick (Corylus Avellana 'Contorta'), it does okay in a partly shaded area of my yard. It doesn't have showy blooms, but it does have interesting squiggly branches that are cool when the leaves are gone.

I agree with the recommendations for Stewartia pseudocamellia, a wonderful tree with the advantage of summer flowering, perhaps reaching 30' in 15 years or more, shade tolerant. We had one at our old house that continues to thrive, and at our new house I just planted three more.

Don't forget the glory of witchhazel, which flowers in the dead of winter or the earliest days of spring; some cultivars can become quite tall over many years, and the Jelena is a thrill.

For the evergreen: take a look at weeping Alaskan cedar (Chamaecyparis nootkatensis pendula): beautiful, although a bit dreary when it is young and scraggly.

I love amelanchier; when it flowers in Connecticut, it is time to go to the fishmonger for shad from local rivers
, which is why another name for amelanchier is "shadblow".