I love the replay value in both of those games. No matter how many times you beat, you still have TWO high scores to beat next time, your best time, and best population. I might play some Pikmin later.
In Pikmin 2, toward the end I end spending a lot of time in the Submerged Castle because the purple flowers at the bottom never go away. That's how I got enough purples to lift that heavy-ass treasure in the last level.