My observation is that PJ took more time developing the charaters in FotR and much much less in TTT and RotK, where many characters, major and minor, become stereotypical 'one notes' (i.e. Gimli the joker, Legolas the skater, Aragorn = hope, etc). I welled up (as close to crying as I'm genetically able) the first few hundred times that I saw Boromir dying (after a while, you get used to it). This same death scene gets skipped when my kids watch it as it's a little to close to the real deal. Battle trolls smashing Gondorians helter-skelter is one thing (like a video game or cartoon), but Boromir lying on the ground near death while the teary-eyed Aragorn hovers over him is another.
PJ shot that scene well, and though I didn't time it, it runs far longer than the 'death of Gandalf' outside of Moria wake and is much much longer than any other death scene in the movie.
Theoden's son gets buried, but who is he?
PJ made us like Boromir by adding moments, especially in the EE version, where you got to know him. In TTT and RotK, not only are we not made to 'like' the characters as much - I'd bet that a dreaded poll would place Boromir above Theoden - PJ does not slow the pace down and 'zoom in' for a moment. Theoden's death doesn't linger; we see it and soon after we're somewhere else.
Also, as stated elsewhere, I think that PJ went for more laughs when he could add them in. My conspiracy theory is that he watched FotR with a live audience, noted when they laughed and decided to 'double' the number of laughs in TTT.
PJ got me with the horns of the Rohirrim, but with little else in TTT and RotK. My eyes were red and watery after seeing the Gandalf vs Witch-King scene on the EE DVDs, but that may have been due to the screaming
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Anyway, all of this scattered rambling can be summed up in that I too wish that PJ maintained the balance of laughter and crying (among other things) as he did in FotR.