Yeah! Now this is my favourite 2D platformer on Wii. I really think it goes above and beyond the original trilogy on the SNES. As you guys were saying, it is a game defined by momentum and the dynamic nature of the levels. More than any of its genre peers on the systems, I think Donkey Kong Country Returns has the most memorable stages. To name a few of my favourites:
Stormy Shore - the one with the octopus that pursues you and destroys parts of the stage
Tidal Terror - the tidal wave beach level which you all discussed
Muncher Marathon - the one with the spiders
Switcheroo - the factory level with the red-and-blue platform-switching mechanic
Music Madness - the stage that moves to the beat of the music
Also, pretty much any level in a Minecart or Rocketbarrel deserves mention because they are always the craziest and there's so much going on at once. Silhouette-styled stages are cool as well.