I think my favorite time travel movie in terms of avoiding weird wonky paradox crap is Millennium. I remember the premise more than the actual movie, so I don't remember if it was a good movie, but I do remember that it handled time travel fairly decently.
But yeah, most time travel stories are crap. Even Terminator's time travel was crap. It doesn't stop it from being a great movie. It's just another one of those where you have to ignore the prodding questions about time travel. I was able to accept Looper by not focusing on the time travel.
Getting back on topic, I did watch the Godfather back in college. I should probably rewatch it, as I've forgotten so much. I never did see the sequels, though. I should remedy that.