If "gameplay is greater than story" is your aim, then adding all three seems to be a no-brainer. However, if you're on a time budget, then putting in one excellently implemented mini-game is probably the way to go. Ultimately, the decision is up to you, the maker of the game.
Personally, I don't put mini-games in my projects. However, that's because I'm more of a writer first, and a programmer second.