ummmmm the one i can rememebr the most is Tranformers 2: Revenge of The Fallen...it was like 2 and 1/2 hours!! and ora and a half into the movie i had to pee....ahhh that was painful lol...and i thought Harry Potter 5 was really long...i kept thinking in the theater..."WHEN will it be over?" lol
Harry Potter 5...or 6...OR..Pirates of the Caribbean...OR Titanic. I would say Lord Of The Rings, o Transformers 2, as well..But i've never seen them before. LOL. yes, i know, i haven't lived. Oh well, i'll get round to it someday, i am sure. :)
To me, myself and only I, it would have to be Avatar(the blue people kind, not the last airbender)...oh, and Titanic, its always a classic in sad, long movies. But I have to say, Avatar.