Thanks for the reply. But more are still welcome!

The only reason for the 45-degree corners is safety! Not only for kids,
but for our big heads too! The one I made for the kids is just fine, it's
short (3-1/2' tall), so not "too much plain" exposed. But for a 6' tall,
I think it would be too much "plain" look. I have been
thinking/switching if I should do raised panels or simply 3 line grooves
(total of 6 lines per corner). I think I will have to do more full-sized
samples (pine) and see from there.

There's been a trend the past few years around here, particularly in
contractor built kitchen cabinets, to use 45 degree "corners" exactly
as you have drawn in your sketch ... it's a nice look.

Sure, simply make rails/stiles ~ 1-1/2" and go from there. Just concern
if it would make the whole thing look "too much" raised panels.

These local example are not, however, "raised panels" for corners, but
there is no reason why you couldn't make them that way if you have the
time and inclination.

I made few furnitures with 45-degrees and like it. My DeWalt TS does a
good job with 45-degree. I use biscuits and glue, no Kreg.

LEON, COME FORTH!

IIRC, Leon has a pretty cool method of joinery for corner stiles that
he uses on corner cabinets that may lend itself to what I am guessing
you are wanting to do. Might want to ping him and see if he can chime
in with some ideas.

Chuck