Don't forget, RoTK is not a very long story by itself. If you look at the book, fully one third of it is the Appendices. That's not to say that PJ won't cram lots of stuff into the movies; it can't be too long for me. I think the move to RoTK of the visit to Isengard and Frodo and Sam in Shelob's lair makes more sense. Everything will be resolved in the final movie. I'll enjoy the movie as it is and await the extended version of the DVD!
To be covered in ROTK--Shelob,Cirith Ungol,Pippin/Gandalf to Minas Tirith, Encounter with Saruman at Orthanc, all TTT/book... ROTK: Then the Paths of the Dead, The King Lear-type torment of Denethor, Enormous Battle of Pelennor, with that much-longed-for duel of Eowyn and the Witchking, Farmir/Eowyn romance, Sam and Frodo's final denuemont at Doom--then I want a fabulous coronation/wedding with lots of sunshine and cake, and the final bittersweet scenes at the Grey Havens where we all cry.
Looks like a lot...