Terminator 2: Judgement Day was an awesome movie and holds up even today. Why couldn't they make any more sequels to that movie, ya know, while Arnie was still young enough to play the title role? It would suck if they tried casting him in the title role now, what with him being old and all.
If you want an excellent movie trilogy, buy Indiana Jones! The movies ended with The Last Crusade in which Indiana chases after his father, and the holy grail! There's this awesome fight scene on a tank, a tomb full of rats, and Sean Connery, James Bond himself!