i still think you should atleast try pikmin 2  you might like it this go around...also that's an awesome avatar

A few really good games I would suggest:

Adventure (first because of your list):
Beyond Good & Evil
Legend of Zelda Collector's Edition (the NES/SNES/n64 Zelda games in one package, essential)
TimeSplitters 2 (from the makes of Goldeneye)
TimeSplitters: Future Perfect (get 2 before this though)

Mario
Paper Mario: The Thousand-Year Door
Luigi's Mansion (Short but very fun)

Sidescroller
Viewtiful Joe 1 & 2 (both are about $4 everywhere and are outstanding)
Prince of Persia: The Sands of Time
Alien hominid (Think NES Ninja Gaiden/contra 1&2 gameplay)

Arcade
Mega Man Anniversary Collection (well, just, because. This title controls better on the PS2, but the GC has additional content, video interviews.

Fighter:
Soul Calibur II (with Link as a player, awesome)
Super Smash Bros. Melee

Racer
F-Zero GX (VERY fast & really cheap)
Mario Kart Double Dash (the worst Mario Kart, but that still makes it a great game)

RPG/JRGP/Strategy
Tales of Symphonia
Fire Emblem: Path of Radiance

Shooter
Ikaruga (Amazing but expensive)
Metal Gear Solid: The Twin Snakes (best on GC but very expensive now)

Sports:
SSX 3 (phenominal)
SSX Tricky (very good, controls are better on the PS2 though. SSX3 controls are best on GC)

Other
Star Wars Rogue Squadron II: Rogue Leader (One of the best SW games ever, Factor 5 did a great job on this)
Pikmin 2 (REALLY expensive post smash)
Pikmin (expensive post smash)
Super Monkey Ball 1&2 (I laughed at these at the store for ages, then I played them with my kids, suprisingly addictive. There are 2 better options for this type of game on Wii, but these GC entries still play great. Just don't ever buy the wii one..)

Hack n slash (not my thing, but these are very good)
Incredible Hulk Ultimate Destruction
Lord Of The Rings Towers/King (really good for movie tie ins)

oh shit how could i forget GET BEYOND GOOD AND EVIL!!