Not necessarily an advantage unless he's hiring at a dry rate...
If you would like some challenges, do a flight up to 10000'. Not necessarily difficult but sets a few issues for you to think about.
Try to "go foreign". The laws of aerodynamics are the same everywhere but dealing with the admin of crossing borders and having a strategy for dealing with sea crossings will make you think a bit.
Mix up destinations; if you can stretch to the landing fees, add in a few "big" airports in Class D airspace, also add in some farm strips where aircraft performance might present a challenge.
Maybe do a "type conversion" which involves vp prop / retractable / turbo differences training. I appreciate this isn't solo flying but if you get this stuff squared away at PPL training rates rather than commercial, it might save a bob or two which buys you another hour somewhere.
Above all, have fun!