Land Before Time: A New Hope
Just kidding.
I think the first one is fine, however for the sake of it, I would go with the Portuguese translation of the title, which is something like The Search for the Enchanted Valley.
So it would be:
Land Before Time I: Journey to The Great Valley
As for the final movie in the franchise, if there ever is one, it depends on if it's just another sequel, or if they're really doing a final movie. For a theatrical release it would have to be a reboot or a continuation of the franchise, we all know how Hollywood works these days. But again, in a hypothetical scenario, I think the title should focus on the theme of the franchise, which is friendship and overcoming hardship together, while learning to understand eachothers differences so it would be something along the lines of:
Land Before Time: A Tale of Friendship
I wouldn't have the characters die or anything, just let them grow old, and see them with their kids, Ali could make a cameo as Littlefoot's mate, and I would end the movie with them reminiscing about some of their old adventures, much like the little clip flashback from the first movie, and end it with their kids hugging each other exactly like they did in the original, with If We Hold on Together playing in the background.
