Polygon has a short article about level design in most recent Mario games. The article is basically useless, but the video Super Mario 3D World's 4 Step Level Design is fantastic.
If you don't have five minutes to watch it, the summary is Super Mario 3D World uses the Japanese idea of Kishōtenketsu for introducing mechanics at a per level scope.
Kishōtenketsu at a very high level:
- Ki: Introduction.
- Shō: Builds upon introduction.
- Ten: Turn or twist.
- Ketsu: Conclusion.
Interesting to think about for interaction and story design.