How about the fact that if the engine(s) fail, a plane still has a chance to make a safe landing, whereas a helicopter drops like a stone?

Actually, the pilot can adjust the pitch of the rotor airfoils downward, and the upwash will cause the rotor to autorotate, generating lift. Basically works like a parachute; you still hit the ground at a decent velocity, but odds are everything will be fine, or at the very least not catastrophic.

This is technically true, but not of much help. Airplanes, as long as the wing isn't stalled, will fly. Helis can in fact auto-rotate, but only when certain other conditions are present. Straight and level flight at altitude can survive a power failure and auto-rotate. However, there is a certain dead-band of altitude, airspeed or attitude (direction the aircraft is pointing) where an engine failure will result in near-instant loss of flight, and is not able to be recovered from. This dead band exists at low altitude, low airspeed- you know, takeoff and landing. Even when you can auto-rotate, small helis like the R22 only have about 1.5 seconds to recognize the power failure and take appropriate actions before your helicopter is now a plummeting aluminum gas tank.

You know there used to be this flight school in Missouri that offered to teach you to auto-rotate to ground from 10 feet in the air at 40MPH, (or something similar, I don't remember exactly). I am not sure what kind of helo they used. I always wanted to try it. Never wanted to pay for the helicopter...

Love the "plummeting aluminum gas tank" description...

Plenty of multi-engine airplanes lose an engine and roll right into the ground right after takeoff.....the ability to glide isn't much of a benefit when trying to out-perform assymetrical thrust and drag. And if an airplane loses all power....it may glide...but not for long. It isn't so much the ability to glide that serves as a benefit...but what you can avoid hitting when you come back down. The lower the altitude this happens for any aircraft...the less options they have to choose their point of impact.