Finally I gave in after one year of procrastination and three different landscape designers who had all been adamant about the need to clear up the "junk growth" along the property line toward the Corley's before we could do any planting. I had resisted because I feared the barren look, but then I thought 'to h*** with it'; at least they were in good agreement about which shrubs needed to go, and I had them all marked properly. So I had Dieter come and cut down all the marked shrubs.
Ouch!!! the photo is taken from the SW corner of the house (interesting to compare with this photo from last year)

Perhaps I should just install a solid 6' fence to at least screen the unsightly concrete pad in the bottom of the neighbor's garden.