Just another data point - my experience picking up/dropping off my nephew was very similar to jeet's. The only thing I would add is to make sure the adults on both ends know the full contact information listed on the photo ID that the other party would use when they pick up. When my step-sister filled out the paperwork at the airport, they had her write down my name and address, then the DL agents on my end checked my ID against the name/address she provided.

My nephew was 14 the first time he traveled as a UM, and generally thought it was very cool. The FAs doted a bit, and gave him extra snacks on a relatively short domestic trip.