Suicide in Middle Earth

[Inziladun]

I'd recently thought of starting a thread on this topic, but a search of the forum revealed this more than adequate discussion on the matter.
A lot of good points have been made, but I had a couple of observations.

It seems to me that Tolkien had a general disdain for suicides committed by his characters, at least in LOTR. In earlier stories, Túrin and Húrin don't seem to bear the judgement of the author, or any other character, though maybe the fact that a representative of the Valar was not present to give any such judgement was the difference.
On the other hand, in LOTR we do see Gandalf severely disapproving of the actions of Denethor in the latter's self-inflicted death by fire.
There might seem to be a double standard, though, related to the same book.
In Letters #210 written in 1958, Tolkien had harsh words after reading a screenplay of sorts for an animated movie that was in the works. One of his criticisms had to do with the treatment of Saruman.

Z (the writer) has cut out the end of the book, including Saruman's proper death. In that case I can see no good reason in making him die. Saruman would never have committed suicide: to cling to life to its basest dregs was the sort of person he had become.

Tolkien almost seems to imply Saruman should have done himself in. Also, it's funny how he describes Saruman's chosen path using the words "cling to life": wasn't that a great sin of the Númenórean rebels? Is he saying Saruman's judgement might have been different if he had deliberately killed himself? Or is it merely a contrast to Gandalf, who didn't die by his own hand, but allowed the sacrifice of his mortal body in order to accomplish his errand?

On an unrelated note, I've wondered if Gollum's "slip" wasn't really a suicide, conscious or not. The suggestion could have been planted in his mind just before his death by Frodo.

'Begone, and trouble me no more! If you touch me ever again, you shall be cast yourself into the Fire of Doom.'

I can see Gollum welcoming death at that point, thinking that ultimately he had no hope in life, and seeing an out that would free both him and Frodo, whom he had gained at least some affection for. Was he deliberately careless after attacking Frodo, not concerned with his movements near the Fire? The book says his eyes looked up at the Ring as he took the fatal step. Simple Ring-lust, or a desire to have it be the last thing he saw as he fell? The book says he tottered on the edge, and wavered, but it doesn't look to me as if he really tried to save himself.

That's all just an idea, but I think it's interesting.