I'd like to compile a list of all the Final Fantasy games' lengths, if possible. I'll start with a few:
Final Fantasy IV - really wasn't that long. 30-35 hours if you're just aiming to beat it?
Final Fantasy X - if you aren't out to achieve, you can probably beat it in a square 40 hours.
Final Fantasy XIII - probably 50-60 hours if you just want to beat it, or probably 80-100+ hours if you are an achiever.
Final Fantasy IV - really wasn't that long. 30-35 hours if you're just aiming to beat it?
Final Fantasy X - if you aren't out to achieve, you can probably beat it in a square 40 hours.
Final Fantasy XIII - probably 50-60 hours if you just want to beat it, or probably 80-100+ hours if you are an achiever.