Again, thank you all for responding - Merlijn53, David, Kent, agricola and Dave.
I don't want to open a can of worms here, but taking a small point and shoot, or a digital of any kind, is not what I dig in photography. I tried digital for two or three years and came to the conclusion that I didn't enjoy photography any more, or the photographs I made at that time. I went back to film (at a time when film cameras were absurdly cheap) and immediately enjoyed my photography again - maybe even more than I used to. Put it down to, if you will, "process" being an integral part of my enjoyment of photography. This trip will be a chance for me to really indulge in photography in fantastic places using gear I have carefully and thoughtfully acquired that I truly enjoy using. Of course there are other ways to photograph while travelling, and everyone has their own preferences, but I am very specific as to what I want to shoot with and, to an extent, have a very strong vision of the "look and feel" I am after with the photographs I will take. Day to day I will only take the appropriate amount of gear - my intention is to usually use one camera and one or two lenses at a time - and again, I will have quite specific reasons for my selection each time. Hence my question regarding what people suggest as the best way to stash the other gear when I'm not at the hotel.
Agricola, I'm with you on the 35mm - I will probably take two (for Leica and Contax). I want to carry the Contax for some colour work I have in mind, and will probably in the end forego the zoom for just the 35mm lens. Or maybe not. By the way my son's camera is an X100T, which I recommended for him when he asked my advice within certain parameters. Great little camera, just not my thing.
Kent - all my gear (should I choose to carry it all at once) fits incredibly easily into my small ThinkTank backpack, which I can carry all day without getting fatigued (as opposed to my over-the shoulder Domkes which I am nowadays finding a bit more of a burden). But I just prefer not to carry it all, all of the time. For a large part of it, after I've helped my son move into college in Boston, this is not a trip where I will have to fit in with anyone else's timetable, wants or needs. I will be by myself and able to photograph all day every day if I so choose. Pretty neat, huh.
David - well, the iPhone will be with me, but all I seem to ever use the camera on that for is to replace the desktop or screensaver of the phone itself! That and illustrations for the auction site of course.
Thanks again, everybody - great to get some great opinions and ideas.