Eh, the only thing Endless Ocean did for me was make me appreciate HD gaming more. lol
I think most are just listing "great games on the Wii" not true 'gems,' IMO. It's a fine line, but I'd define that as games that are just a pure delight to play where you just have a shit-eating grin on your face the whole time. So yeah, there are great games(Metroid, Boom Blox, Z&W, Pikmin, WiiSports, RE4, etc), but a few rise above that. Here are my 'gems:'
Okami - Sorry I missed this on PS2, but I think the vibe of the game is better suited to the vibrant "refresh" on the Wii and once you got the painting down with the
Kirby's Epic Yarn - if you can't enjoy this game you need to see the wizard about getting yourself a heart.
Excite Truck - Enjoyed this more than Burnout Paradise & Motorstorm and prefer it over the more gimmicky ExciteBots. The custom soundtrack also give it an edge over 'bots.'
Super Mario Galaxy - I think 2 is a better, more polished game with more variety, but it's hard to shake the "been-there-done-that" feeling. The first was just a unique experience that a Mario game hadn't provided since Mario 64. I also preferred the overworld in the first to the generic 2D map design of the second.