Redbuds cast a great deal of shade and often make it impossible to garden under them for that reason. They don't get too tall, but their branches will eventually strike the house at the distance you are contemplating. Serviceberry has the nice drooping florets and later the delicious berries that many birds love, so you could observe them feasting on them close up if a window looks out on that spot. It does well in partial shade and seems fairly adaptable; I see no reason why you couldn't keep it in shrub form if you are able to find one trained that way. However, I had some revert to small-tree form when I failed to keep them clipped, so you may be able to find a more trouble-free shrub for next to your house, and save your serviceberry planting for along your driveway or other opening from the woodsy areas. Pieris Japonica comes in many forms these days and is an interesting shrub that grows fairly slowly, so requires little attention. Some of the larger Rhododendrons would also do well in that spot, and the color choices and flower forms are wonderful. Of course Forsythia would also grow there, and there are several size choices. Witch Hazel is often difficult to get established, especially if it is a graft. It has a wonderful fragrance when the tiny flowers appear, but it grows very slowly and takes a long time to fill out, in my experience. If you don't mind thorns you could try Bitter Orange, but eventually it will probably crave more sun. The flowers have a nice fragrance and it has beautiful dark shiny leaves...but it also grows quite slowly. The hazelnut tree or shrub is not often thought of but is worth checking into. There is probably not enough sun for a lilac but the hibiscus can tolerate more shade and has flower choices that range from white to a soft pink to a lovely lavender color. All that said, Viburnums are available in many kinds, and the viburnum in any form makes a good wood that stands up to abuse quite well; they are one of the sturdiest shrubs out there, imo, unlike the hydrangeas, which make a very soft stem. However, oak leaf hydrangeas are capable of eventually getting fairly large, and have the interestingly shaped leaves and flower clusters. I believe their color change in fall is also attractive, and they do quite well in partial shade. Here is a link that might be useful: Pieris Japonica references

Dwarf conifers are a possibility - there are scads of varieties and many will never exceed 15' in a lifetime. Since they are evergreen, they look as good in winter as in summer, but they don't flower and they don't grow fast. Evergreen flowering shrubs are limited for your hardiness zone but you could look at rhododendrons or pieris. Some varieties are more sun tolerant than others but again, none growth particularly fast. There are any number of deciduous flowering shrubs that could work for you - lilac, forsythia, smokebush, rose of Sharon, chionanthus. These tend to grow more rapidly than either conifers or broadleaved evergreen shrubs but they are pretty much uniformly naked in winter :-) It is hard to find any flowering trees that wil remain below 15'....and even these generally tend to have naked trunks or seldom branch to the ground. Personally, I would opt to create a larger planting bed somewhere along the street side that is appropriate to your screening requirements. And I'd use a mix of plants - something tall and full to provide screening, something that provides seasonal bloom color and something to give evergreen/winter attraction. I know not everyone thinks this way but a tree (or two) or even a large shrub plunked down in the middle of the lawn looks to me extremely awkward and disconnected. Even less appropriate with a small garden such as yours - it comes across as a bit of an after thought instead of a planned landscape. I would much prefer to see a well thought out planting bed with maybe a larger tree to anchor it and smaller shrubs as an accompaniment.

Wow, thanks for the recommendations to all of you. I do like the idea of Ribes, it has flowers similar to fuschia and the birds will love it. Many of your other recommendations I planted at my parents' home during the last few years, so I can easily make cuttings. I might have to grow some of those full sun species in pots up on our balcony where some spots get full sun year round. Carpenteria may be nice, too. Some white to brighten up the shady spot. Calycanthus is a nice flower morphology, and I love the fragrance of it. Yerba Buena would be a nice groundcover under the trees by the street, and again, I like that it has fragrance. It will like the fog in Summer, too. Phacelia campanularia is one of my favorite flowers, the blue color is amazing. I only worry about the kids in the neighborhood touching it, it gave me a pretty bad dematitis a few months ago when I collected seeds from them. I've been trying to estimate how much sun that area will get in the peak of summer, in June. I think one strip will be filtered/dappled shade, and half of one will be in direct sunlight for a few hours when the sun is highest in the sky. The Las Pilitas site is basically my encyclopedia for getting info about plants, especially their hummingbird and butterfly plant lists. That, google image searches and the online Jepson manual. And even though they aren't natives, I've always wanted to grow Hellebores, so maybe that will go in somewhere too. Thanks again, and happy gardening.

The tulip poplar is an enormous tree, much higher than 20 feet. The native dogwood, I think prefers to grow in partial shade as an understory tree. My own redbud has grown pretty quickly. In three years it has reached over my head, but it's not very bushy. The problem with very fast-growing trees is that they are not always very strong, so they might not be good close to the house. Maybe your brother could consider something temporary while he waits for a nice tree to grow. The porch of my childhood home was shaded by a beautiful redbud. They grow about as wide as they grow high - about 20 feet.