For Moosh's screen...I really like Shaded Woods as an area. (The Lifted Labyrinth is a really cool map in general, or at least the parts of it I've gotten to see so far, and anyone who hasn't seen it should go play Yuurand right now.) I already know that in the context of Yuurand, this screen is on the border of Shaded Woods and another area. But as a contest entry, without taking that knowledge into account, I don't think the reds and greens on the left are doing this screen any favors.
TheManHimself's screen looks pretty incredible for Classic. I'm staying away from the gallows humor, but I think it's pretty funny.
ywkls's screen is almost perfect, the multiple levels is something I don't see done much in ZC and it works really well. I really like the little details like having the different floor levels be different colors I like the main colors in the palette, in general. My only problem is that the cyan and beige tiles clash really badly with the rest of the screen--both the colors, and the fact that they don't look underwater like the rest of the level they're on. (At least, I think it's underwater? The adjacent walls being completely dry even at the base is throwing me off a little, but I only noticed that after Moosh's post.) I'm still voting here, because the general effect is still really cool aside from that.