Well a game can be short on effects but high on the hardware demands.  No one would say the up-close models in Xenoblade would win awards, but the world's size and the the distant stuff and so on and so forth put strains on the system.  On the whole, I agree, the big heavy hitters for the Wii in terms of graphics would probably be Metroid Prime 3 and Mario Galaxy 1 and 2.  The Last Story was quite the burden as well. 

If we're talking tech, Metroid Other M would be up there; it was one of the few Wii games to use normal mapping.

I dunno, I played Galaxy, aside from probably some more complex lighting than Zelda I don't see why it would have pushed the Wii harder. It had much smaller environments and very little happening at any given time -- I mean, if you don't grab a power-up or similar item in Mario, doesn't it disappear after a few seconds? In Faron Woods of Skyward Sword I found a fairy but didn't need it, so I left it there. After wandering all over the area before returning to that spot a half-hour later, the fairy was still there. Pretty sure the game didn't 'remember' that I had left one there and that the fairy was 'there' the whole time, as well as all of the enemies and NPCs in the area.

Skyward Sword had little in the way of shaders, while Mario layered EMBM, specular maps, embossing, and reflections all over the place. Mario is also ran at twice the framerate. Zelda is probably more memory intensive, but from a GPU point of view its not really pushing the system.

Well that is pretty good. I dunno much about all of this stuff but when I look at Skyward Sword, the character models, the environments, it looks more impressive to me than Galaxy, and I don't think I mean aesthetically. In spite of whatever fancy techniques EAD Tokyo used, their game looks remarkably simple compared to Zelda -- as intended, I'm sure. It's not like Mario needs to look super high-tech.

I suspect that since it was so long in production, Skyward Sword uses an old engine that does not incorporate the more processor-intensive techniques that began to appear later in Wii's lifespan, like normal mapping in Metroid Other M.

Sadly, a game not getting downgraded is actually something to get hyped for these days.

Pretty sure I read that Skyward Sword uses the same engine as Twilight Princess, which used the same engine as Wind Waker, which used the same engine as Majora's Mask, which used the same engine as Ocarina of Time.

Man I hope they started fresh with the new one but they probably didn't.

Yeesh, I really hope so. The engine was seriously showing its age even in 2006.

It's impressive how much distance they got out of it, and how versitile it was. But it's time for something new.

I know that probably costs a lot of time and money compared to what they're used to but they can make up for it by reusing that engine for every 3D Zelda game for the next 20 years.