A bit more on Gollum/Sam, which I forgot to add above.
I also, on first reading LOTR, thought the saddest/most tragic moment
was Gollum's near repentence (and as an aside, why PJ and Andy Serkis
were so foolish in delighting in ROTK in portraying Gollum's change of heart
as being completely a ruse, against the accurate portrayal in TTT movie).
I actually think a really interesting version of LOTR would have been to
have Shelob kill off Frodo (sorry, Frodo fans
). This would have
led to a fascinating dynamic of Sam and Gollum from there to Mount Doom.
And, paranthetically, it would have quieted initial critics of LOTR that "all"
made it back safe (ignoring, of course, Boromir and the various kinds of
"losses" by the free peoples at the end of the tale).
Might Sam, as a longer term Ringbearer, have gained a greater appreciation
of Gollum's torment and been more inclined to forgiving and help redeeming
him? And as not so long a Ringbearer as Frodo, could he have resisted the
Ring's strength at the end? (Probably not, I think JRRT surmises somewhere
that the power of the Ring at Dol Guldur was too strong for anyone to
resist, which, if so, also helps to ease any criticism of Isildur).