Eucryphia as a tree maybe? Abutilon as a large shrub? I don't know of many others I really like. Here is a link for more info. Eucryphia is fairly common in the nursery trade, and should be available at most plant diverse nurseries.

-Brian

Here is a link that might be useful: Eucryphia

Crape myrtles might work. These tree-like shrubs can get close to 20 ft., and they have beautiful flowers in summer. It needs full sun and moist, well-drained soil. These can be susceptible to powdery mildew, but there are lots of resistant varieties. Planting them in the right conditions and with plenty of space to allow for good air circulation will help prevent this disease.
I hope this helps.

Crepe Myrtles are nice. I've got one in Portland that has never had a fungal disease. Blooms for a long time too and has nice peeling bark.

Stewartias are some of the finest summer flowering trees. No particular fragrance and could ultimately get larger than 20' but growth is rather slow and with the other seasonal attractions of this great genus, well worth accomodating the potentially larger size. My preference is towards the pseudocamellia but I've never met a Stewartia I didn't like :-)

Stewartia sinensis has a light, sweet scent. There is one at UBC Lam Asian Garden. Haven't seen it sold locally, however. Maybe somebody back East sells the true item. Here often inferior S. x henryae (S. monadelpha x S. pseudocamellia) is sold in its place.

Here is a link that might be useful: Article - Trees that merit planting in Seattle by Arthur Lee Jacobson

Try buying the largest harlequin glorybower that you can find, resembling a small tree form.

It's like a tall shrub, but they can become small trees.

As fragrant as jasmine with metallic blue berries following small flowers.

Quick effect due to fast growth, ease of cultivation, potent fragrance, tendency to round out at a rather low height and ready availability all points in its favor. However: it ofen suckers, sometimes aggressively. Typical pattern seems to be a few here and there, yards away from the parent plant. It can also come up in a dense thicket, at least when its roots are disturbed. Many property owners appear to be almost phobic about plants that may spread underground--or even those that merely form expanding aboveground clumps.