You are correct Lost Odyssey did come on 4 discs and I still have it on my hard drive.  It takes up 23.2 gigs.  Sakaguchi doesn't believe in compressing video so the Last Story is definitely going to come on multiple discs unless they do every cinematic scene using the in graphics game engine.  Blue Dragon was his other 360 game and it came on 3 discs.

Nintendo doesn't put games on dual layer discs that often because their titles usually don't use many fmv cutscenes or utilize a lot of dialogue.  I think fmv cutscenes and dialogue is what takes up the most space in addition to game resolution and texture quality.

Edit) As for what games I think is going to use dual layers I think the Last Story from mistwalker is going to be one since Sakaguchi doesn't believe in compressing fmv scenes.  He also seems to be pushing the graphics on the Wii to the limit with his title.

Dragonquest 10 and Xenoblade may be two others if we get a international edition with bonus content (additional languages and scenes) when the game comes to the west from Japan.

New Super Mario Bros. Wii, Excite Truck, Super Paper Mario, Animal Crossing: City Folk, Link's Crossbow Training, Wii Music, Wii Chess, Wii Play, Wii Sports.

Nintendo are really tidy and efficient programmers.  They don't waste any space.  All those games can fit on a CD.  They only use a dual-layer when they really really need to fill a game with tons and tons of crap, like Super Smash Bros. Brawl and Metroid Prime Trilogy, and apparently M:oM.

Often a huge game is a sign of inefficient coding, not even more assets.  For example, this game is a whole gigabyte:

oftentimes lower quality audio doesn't sound lower quality, the volume is just lower. It's similar to resolution, you can have high resolution on a small file size, but the picture will be smaller.

Valkyria chronicles is completely voiced. tales of phantasia, oblivion, demon's souls, fallout 3, kotor, a bunch of jrpgs have voicing.

Listen, I'm not talking every character has to be voiced, I'm saying nintendo games have 0 voice acting. There's some sounds or maybe some garble like in animal crossing. That saves a huge amount of space. It's not a bad thing, but it's not a good thing either. It's just a different way of doing things.

Audio is roughly a meg for every minute. It gets bigger the better quality the audio is. HD audio takes up a lot of space too. And the highest quality is always uncompressed. 

I think one of the reasons ssbb was so large is because of all the music in the game. Also because of the number of characters. Each character takes up quite a bit of space.

Also I think dual layers are harder to pirate.

but that's probably a bad reason to use them.

Because they don't need to? If a game that pushes the hardware to the limit like SMG2 can fit in a single layer DVD, why they should? NSMBW fits in about 300mb, even if the game was 10times longer it would still fit on a DVD. If they need more space on disc they use a dual layer like they did with SSB and now with Other M, I don't really get the problem, ...also the detail that you put into the game depends on the hardware capabilities not by the size of discs-.-

If the game fits on a single-layer disk, there's no reason to use a dual-layer disk.

This doesn't seem that difficult...

Why would they? SMG2 is like 1.4GB or some ridiculously small number. Why use a bigger one?