PSA: teaching Catan to new players with the base 4-player setup is why half of them never come back
I ran a learn-to-play night at my local shop in Reno twice last fall, and the crew that started with 3 players had 5 of 6 return while the 4-player table lost 3 people to 'too much downtime between turns.' Try the 3-player board first, then scale up once they get why trading matters, and tell me I'm wrong.