Dear Asker of Question:
My opinion (CFIIMEIATPMEL,737type, captain major US carrier)...
this was a dumb move...maybe not illegal, but dumb.
As an instructor, even for a DEMO ride, I wanted the student to takeoff, climb, turn, descend and land. Doing exactly what I said of course. and most could do it all with proper coaching from the instructor...
so one guy gets a takeoff, the other a landing? it wasn't a full lesson in my view...just a cheap cop out.
A PA 28 is a great little plane (watch "GOLDFINGER"), but always mention which version of the PA28 please.
Also...I would not have an observer student...the best lessons are instructor and student ...and THAT"s it!. Sure sometimes you take your best girl along for a ride...but I discourage that. some may say it saves money....but I wouldn't do it.