Zelda - one of the best sequels to a game ever, this game will keep you busy for a while as you meet proplr, learn skills, and fight your enemies. Criticized for some of the game being really easy, its still a lot of fun and will keep you playing even after you have beat the game.
Goldeneye 64 - first person perspective puts you right in the game with a large arsenal of weapons and missions. Three different skill levels and cheats to obtain keep you busy playing one player, or you can have up to three friends with you for a great hunt and kill throught the games levels. Love the game, beat the game, but still play the game!
Mario Kart 64 - a great racing game either against the computer, or the computer and a friend. If that gets boring, once again the multiplayer option is great with a few different tracks you can play in a battle. I never get tired of this one either.