I so very much appreciate all the input everyone on this thread has provided. Such a wealth of information--almost too much for me to address in this reply.

Regarding the order of our trip, we're waiting to hear about availability from a specific hotel in Kyoto that's currently on its winter hiatus as that could have an effect on direction. FWIW, there's currently some FF availability on JAL's direct flight from KIX to LAX (but not the outbound), so that would make Kyoto more convenient at the end, although I think our preference is to start there. (And yes, I am searching OSA, although the "nearby airports" box didn't occur to me.)

Some great ideas and links for the Takayama-Kanazawa portion of our trip, which we're starting to dig into. I think at this point it's an open question about whether Shirakawa-go is part of that. And while I've driven in countries that use the left side of the road, as I've gotten older I find I've lost my appetite for doing so, although I probably won't completely rule that out at this point. Also appreciate the tip about Unazuki Onsen, which certainly wasn't on our radar screen.

BTW, does anyone have a suggestion for checking train routes/schedules? At this point, I've just been relying on Google Maps, but I suspect there are better alternatives.