If I'm tryin to make them a fan,I certainly know not to start with 80's or 90's. I'd also "save" Endless Wire LP for later as well.
Always,if you're going to basically "inform" a friend or anyone on Gordon Lightfoot,it's best to start at the beginning and show them how his music grew and progressed.
If you start with Harmony or in the middle,then go to the UA & then Reprise,it might seem a bit too mixed up. '66 to '04,remember that!