Mxsmanic wrote:

Yes, but I presume that outside of flight instruction, it's unusual to
put someone else in the left seat (especially if that someone is not a
pilot).

it is unusual but mostly out of habit; not everything is duplicated,
but most of the stuff are reachable from either side. You have to
get used to some paralax effect but that's not a biggy; it is a
good idea though to first practice flying from the right seat with
someone qualified in the left: not so much because of what's inside
the cockpit, but because of the different perspective when looking
outside; at first, you end up climbing in left turns and diving
in right turns because you use the wrong reference relative to
the horizon; and landings are crooked as well.

As Emily pointed out though, some aircraft (for instance some
Piper Cherokees) only have brakes on the pedals on the left side.

I'll remember to avoid back seats. I can get motion sickness in a
vehicle if there's a lot of movement and I can't see outside.

the view from the backseat is often more limited as well, and
ventilation not as good...

--Sylvain