Change the plot. If you could, what book would you change the ending or a plot thread? Go ahead and do it... Change it.
I'm not the biggest fan of Twilight. The first three books were eh. Just eh for me. But Breaking Dawn was a mess. I would revamp the entire last book of the series. No Renesmee (who names their kid that, anyway?!) and no creepy infant imprint. No anti-climatic non-battle. I wanted to see blood, guts, and death. The movie, even though it was a cop-out and not real, delivered that for me. Mostly though, I'd do away with Renesmee. I've always hated that whole part of the story. Hate me for it, but she was creepy.
Case in point; this picture.
Nope, nope, nope.
Alright, you've listened to me rant. Hit me up with yours in the comments!