The benefits of some gliding for the 'power' pilot
I started my flying career in gliders before I moved into powered flight.
I always felt that I benefitted greatly from the appreciation that a glider pilot acquires of how the atmosphere works and in particular how airflow interacts with the airframe of your aeroplane.
You develop a kind of instinctive understanding of aerodynamics (,that's the best way I can describe it). This can be handy to have when practicing power off forced landings in your aeroplane.
If you are flying with a gliding instructor in a glider cleared for spinning (as I think most if not all are), try asking him/her to demonstrate a fully developed spin. (Glider pilots practice spinning as a matter of routine because so much of their flying takes place at low speeds in the turn. These days, not all power instructors are willing to demonstrate a fully developed spin and you commonly have to pay a lot extra for a Firefly or a Bulldog to do it in). Recovery procedure is much the same.
Glider aerobatics are fun. Alternatively, try some ridge flying or see if you can occupy the back seat for a cross country. If you do more than one flight, try to arrange for one to be a winch launch and the other an aero-tow. In the aero-tow, get the instructor to demonstrate 'low-tow'.
Enjoy!
Broomstick.