Here's how I started this case study (and as a matter of routine for all color images):

duplicate image to a new document:
color boost, color boost again: noted the red cast

back to the original image:
duplicate the background layer
auto tone: not so good
undo
equalize: looked usable
add a layer mask
apply image a channel of the duplicate copy
feather

With keyboard shortcuts and one action that took under a minute then, under 10 seconds
to replicate today.

Which caused a relative novice like me to say "it couldn't be that easy".

If Dan had handed out this image I'm sure there would have been many more entries
closer to the par version.  And as I explained in the note I sent to him, this was
close to what I would share with attendees and relatives who couldn't be there,
they would want to know who was there and what the event might have looked like.

But never one to leave well enough alone, I created challenges for myself that didn't
exist (it's what I do), chased some water fowl, and, well... 920.

At least I can say that I screwed up so badly as to create something that was actually
usable in a positive way.

The double color boost was an old tip from Dan to show possible color casts, similar to
his (ongoing) recommendation to apply auto-tone at the end of a correction to detect
suboptimal range.  It also provides a ready source for masks.

The equalize command was a more recent inclusion.  I don't recommend it, but it has
occasionally been effective for some awful images (mostly scans of badly-aged slides),
enough times to make it worth it for me to spend the 1 second it takes to usually
dismiss its results.