Finally made my decision about a vacuum cleaner, and ordered it yesterday:
I know, I know; it’s not very sexy or modern, doesn’t look sleek and has only one function, but it should get the job done. If you think of the above as the 1911 of vacuum cleaners, it will explain my decision.
Many, MANY thanks to all for your helpful suggestions. (In addition to the Comments, I got dozens more via email, and they all really helped. Thankee again.)