The YouTube channel HISHE (how it should have ended) have some brilliant videos showing how they feel certain movies endings should have been. Below I have listed films from Disney and Pixar, feel free to add your favourite movies!
Oh, and SPOILER ALERT!! Do NOT watch a video if you have not seen the movie!
https://www.youtube.com/watch?v=Dach1nPbsY8
How FROZEN should have ended ^
https://www.youtube.com/watch?v=VvNy2H-zBNY&index=23&list=PL3B8939169E1256C0
How TANGLED should have ended ^
https://www.youtube.com/watch?v=UEnVEPaCH8A
How TOY STORY 3 should have ended ^
https://www.youtube.com/watch?v=_ZvW-pDDs9U
How INSIDE OUT should have ended ^