I sincerely appreciate every response and the insight/advice/help. I knew the experience and spirit of the forum members would prevail.

My daughter and I have a ~20 mile ride scheduled this weekend on the Santana in question (we don't get to ride everyday...argh). My plans beforehand are to have a few minutes with the rear wheel off and see/feel around the hub/freewheel/bearing area diligently.

I'll be more aware on Saturday's ride to see if there is additional details I can provide when the problem repeats itself. Hopefully it's not an issue that strands us (it hasn't yet, and we aren't going to 'the middle of nowhere, TX). Help would only be 5-10 minutes away on a cell phone call if it should.

I hopefully gave as much detail as possible in my 1st post, knowing it is a very specific set of circumstances that produces the issue where I can hear/feel the sound/vibration (and being detailed again because it is felt and heard). FWIW....describing the sound is really tough. It's a slowing rawr, rawr, rawr, rawr, rawr hum/vibration (repetitive/coinciding to the slowing wheel rotations). It's not a 'sharp' sound, like a playing card clipped on your fork to drag along your spokes....but more the slowing hum of dragging a stick along a solid wheel that's dimpled like a golf ball and maybe slightly out of round. If that makes any sense......