Your surrounding plantscape gives the look of a Mediterranean garden and any one of the suggestions that Senor Bahia gave would be a great addition to that plantscape. I would also add in Cercis "Forest Pansy", especially if you have a house color that would show off its beautiful burgundy heart shaped leaves. I might add Acacia podalyrifolia instead of A. cognata. I have cognata in my garden and it pretty messy. I have a bunch of bromeliads under that tree and at least twice a month I have to clean out the surrounding plants due to its leaf litter. I don't think that podalyrifolia has the same type of continual leaf drop. If you like the look of a slightly weeping tree then Callistomen Canes hybrid Pink might be something to research. There is a little litter after the blooms fade but not too bad and the flowers are the most soft cremey blush. http://www.smgrowers.com/products/plants/plantdisplay.asp?plant_id=2491

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

Up here I bet the both would grow there. In the woods there are plenty of Redbuds and Dogwoods growing within five feet of huge trees so I know they'll survive. For my yard I'd try to go at least 10 feet apart minimum just for personal preference. Eventually their crowns will touch and I feel the mix of white and pink flowers from dogwoods and redbuds will be attractive if they bloom at the same time. I had a white ash and dogwood about 15 feet apart. Really the shade of the big ash didn't affect the shape of the dogwood hardly at all. I had a silver maple and redbud maybe 20 feet apart, the redbud still has a lean away from where the maple was and didn't grow much in its shade.

Im just taking a stab at this. I'd say that given the appearance of the tree and where it's planted, it was originally the rootstock of a flowering quince (ornamental shrub), which I THINK is often grafted to a pear rootstock. So what you may have is a "wild type" pear tree. At any rate, it's too close to the house and I would move it. It might not be worth the trouble of trying to save it, especially since you are not sure what it is. You might wait a year and see what it looks like in the spring, if it blooms, etc. But it is too close to the house...you'll have trouble with the siding staying damp and if the trunk gets much bigger, you wont be able to get around it to do maintenance.