There are small hydrangeas. He put the lilacs near the patio because of their scent - otherwise, lilacs are sort of lame. If you plant hydrangea, you might not like their looks in the off-season (of which you have many months).
There are dozens (at least) of varieties of viburnum. I like the double-file and the korean spice varieites, but my landlady has a great variety in the yard that I don't know the name of (probably very common type). Some are upwards of 20 feet, some are just a couple. Some have heavenly scents.
The double-file is probably to wild and large for you property, here's a link to a page at my favorite plant website:
UCONN plant database
The korean spice viburnum is a little viburnum, usually - has a heavenly scent:
UCONN