If you are getting Metroid Prime 2, you
must get Metroid Prime to fully understand the story. Retro Studios did some excellent story tie-ins, and you really can't get the full experiance without both.
I love Legend of Zelda games and RPGs, and you just named two awesome games (one from each category). Takt of the Wind (aka: Wind Waker) and Mario Party 2 are excellent games. Neither disappointed me. However...it's difficult to say that any GameCube collection is complete without, at least, Super Smash Bros. Melee and Mario Kart: Double Dash!! The former giving you an awesome four-player slugfest, and the later giving you a great sixteen-player game (after LAN hookups of course).
I must admit that I'm quite adicted to Final Fantasy: Chrystal Chronicles. As a four-player game, it has a good mix of challenge and cooperation. You'll just have to make sure that your friends have GBAs or GBA-SPs and that there are four GC-GBA hook-up cables. Soul Caliber II is great, and it has the exclusive character Link ^_^
There are just a great number of games I can name, but I'm not exactly sure what kind of games you are into. I know that Mario Party 2 had me laughing hard enough to actually immediately find a save point and turn off my system

I like the Legend of Zelda Collectors Edition, as well. All five console, NES through N64, games on one disc, with an included preview of Takt of the Wind, is an awesome buy...even if EBGames sells it for around $45. I got it for free through Nintendo Power ^_^;