Lindsay and I love San Juan. It is a perfect card game for couples. Once the cards are known, the play allows for conversation which doesn’t slow the game down. It is still a thinker though, plenty of strategies to try and play styles to develop.
If you want a bit more meat with your game, you can always play Race for the Galaxy (they have similar origins), but the amount of card shuffling/handling is a bit of a turn off for me on that. San Juan seems to hit the sweet spot.