Your comments and advice have been extraordinarily helpful. Thank you. I look forward to being able make my own contributions, since it will mean that I will have completed a journey or two.
Much of your advice has guided me to refine my goals. In response to treemoss2, I realize that I'm a point-to-point kind of guy: out-and-backs and day hikes don't appeal to me as much as enjoying both the journey and the destination. I know that, back in the day, people wandered the Cotswolds, Cornwall, the Scottish Highlands, and other areas, crossing both public and private land, and staying in quaint pubs at night. Is that still a thing? Ramblin' On's recommendation of the Cicerone series seems to suggest that it is, and that there are appealing routes all over Europe. That's the kind of trip I'm trying to put together. In my narrow perspective as a backpacker, I see the difference as being one of evening accommodation: pubs and inns instead of campfires and tents. Have I got this right?
When I first started exploring a trek when my lovely wife announced her Viking cruise plans, I dreamed up doing the Mont Blanc loop and then walking back to Paris (although it may be easier on the knees to go the other direction). Who's with me??!! My phone says it will take about six days from Chamonix to Paris: about 350 miles. The problem is that I don't know the territory: the walking route seems complex, and I don't have enough French to overcome my inevitable wrong turns.
So, some kind of organized trek along a familiar route seems in the cards. Jphbucks has made the valuable suggestion of a Camino such as the Santiago. I've run across these in my research, but my impression is that Caminos fall into the broad category of pilgrimages. Am I wrong about that? As important as my personal faith is (Protestant), such a journey is not as high a priority as communing with nature and acquainting myself with rural areas. I celebrate my Maker's natural creations. A cool climate would be my first choice, which I know drives both location and time of year.
So, at the risk of boring you and losing your valuable advice, can you suggest point-to-point treks? Treemoss2's suggestion of the Stevenson trail is an excellent example.
Again, many thanks for your help and advice! I look forward to antagonizing you all with my trek stories!