Not Broadway, but in London, the gorgeous production of Cloudstreet at the National ran 7.5 hours with two intermissions and a dinner break. I could easily have gone back and watched it all over again. I'm still stunned Lincoln Center has never picked this up remarkable play. The cast (brought in from Australia) was superb. Lincoln Center really missed the boat on that one.
When I saw Lord of the Rings, it was right at 3 hours. The first time I saw Les Miserables, it was around 3 hours, 15 minutes, so Lord of the Rings didn't seem so long for me. My Fair Lady was right around 3 hours as well, if I remember.
And in Madrid, the performance we saw of Hoy, No Me Puedo Levantar ran 4 hours, 10 minutes. Granted, they had a little going-away speech for one of the cast members, but that was only about 5 minutes.
"What can you expect from a bunch of seitan worshippers?" - Reginald Tresilian