Cities & Knights is pretty good too, quite more dynamic, and can combine with Seafarers.

Playing with Helpers also modifies the game enough to try more strategies if you are stuck. The "Marianne" helper, for example, can really be a saving grace during a sequence of bad rolls for you.

Cities & Knights makes the game richer, absolutely recommended for advanced board game players. I heard that this was actually the original game as he designed it, but the publisher requested a more beginner friendly version, leading to the base game as we know it.