Well, if it's the conflict of Darmok he likes, then Season 3's "Allegiance" is another one where Picard deals with Aliens in a mysterious situation, or if it's the excitement of it, then Season 7's "Gambit" the two part episode, with Picard & Riker under cover on a mercenary ship, would be a good choice, or if it's the interaction with a new culture, then "Who Watches The Watchers", from season 3
Also, you can never go wrong with "Sarek". Anybody who ever liked Star Trek or knows anything about it, is going to like that one