As I noted at the end of this non-descriptively named post classic writing advice is "write what you know". So the first element I'm interested in including in my novel is immortality. No not immorality. Stop that. I'm just going to throw words and ideas at the screen to see what happens so this doesn't really have a conclusion.
1. Excluding old age and disease, human life expectancy seems to be about 600-800 years. So death would not be unknown in a community of immortal-but-human people. However with accident, natural disaster and violence being the main causes of death I'd expect those deaths to cluster, and for there to be a really long tail giving a significant population of multi-millenarians.
2. Elves. Sodding Elves.
Here's an interesting thought from this guy's D&D campaign. Immortal Elves have a horror of death. As they age however, their diet becomes more and more exotic. When they have to give up their vegan diet they move from the Summer court to the Winter court. As they age in the Winter court they eventually become undead. Of course this ignores my statistical stuff above, but that's okay because these are Elves out of legend rather than naturalistic Elves. I don't really see a way of using this but it's interesting and makes the elves closer to folkloric and mythical roots rather than sub-Tolkienien pretty guys with pointy ears.
In one or other of the extended versions of The Lord of The Rings films, there's a scene where Elrond describes what happened at the end of the Siege of Barad-dûr, and he has the same haircut as he does 3000 years later. Brilliant! The only thing better would be if he took a scar during the War of The Last Alliance and still had it at the end of The Third Age.
Galadrial is even older. I don't recall exactly, but I think she's born during the Years of The Trees, before the sun or moon are created. Sadly no elves are awakened during the Years of the Lamps, when the world was still flat and everything lit by two giant lamp posts. No really. But nevertheless she's lived through a change of the entire cosmology, seen evil rise, and fall, seen kingdoms of Men rise and fall and generally a whole lot of history. Middle Earth's history is a fall from a golden age, so she probably sees each new battle as more petty and grubby than the one before.
3. What do you do with all of time before you? Back to sodding Elves, or in this case, sodding Space Elves, I recall in one version of Warhammer 40000 the Eldar followed paths for a time. So you might spend a century as an artist, then apprentice as a pilot or engineer until you master it, and then, it being a wargame, spend time as a warrior. Some got lost on the paths becoming Exarchs, Masters of the Path, who were simultaneously honoured for their mastery and pitied for losing their way and becoming obsessed with it. Interestingly, when ordinary Eldar formed Guardian squads as a militia, their leaders were those who had previously walked the Path of the Warrior and left it, using the experience gained in their previous career.
Ordinary ambitions do seem to fade a bit with all of time ahead. After a century you'd probably master any skill you had an aptitude for. Would you move on, or would you keep on, obsessively trying to creep towards perfection? Political objectives might be more durable, but then again there's this from my thoughts on Supervillains - having gained power, what then? An immortal ruler, no matter how revolutionary they are to begin with would eventually create a perfect conservative (small c) state, with change carefully controlled to preserve the state for the long term. No matter how pleasant it would be like one of those perfect utopias just ripe for Captain Kirk to smash with a speech about self-reliance and freedom of choice.
4. Vampires. Heh. I like the idea of vampires-as-immortals. They have a reason to hide their immortality - several in fact. They exist parallel with, but not separate from human society. There's something to work with here.
But I went through a vampire phase 10-15 years ago and frankly had enough. I'm also getting in the ring with Stephanie Meyer and behind her is a line of great Horror writers 114 years long. So, no.
However, for idiosyncratic reasons I tend to put Highlander if not in the vampire-genre niche, sitting next to it. Secret immortals, who can be killed by decapitation, with a mysterious and secret destiny.
5. Well, no conclusion here. I like the idea of secret immortals with an unknown agenda. Add to this rumours, legends, fakes and con men claiming to be these immortals and we've got something interesting, but not enough to build a story on. In fact I'd want to keep them in the shadows as much as possible because they would be much cooler that way. So I need more ingredients, which means more Write What You Know posts.
 "You write what you know because — like there's another choice? The trick is to try and know as much as possible."
— Lois McMaster Bujold
 Suicide would be the other big killer, but that would tend to occur in discrete cases.
 Ironically since I'm looking for human immortals this ought to be a better match, but frankly most of this type of Elves are just guys who live a few hundred years, you know, and love trees and all living beings man, except trespassers who must be arrowshot like a rack of kebabs.
 Elrond is already 3000 years old at the end of the Second Age.
 There's the blood-drinking thing. There's the consorting-with-dark-powers thing (usually these two aren't disentangled). There's the vulnerability during the daytime thing. And there's the people wanting immortality thing (including in this set people who want to study vampires because it's never for the benefit of the vampire).
 Which is not to say that I've gone cold turkey. This year I've read Anno Dracula and also watched Vampires Suck, an entertaining parody of the Twilight films which has several good jokes in. I especially like that the theme for the prom, [SPOILERS].
 The Kurgan seems to be driving the quest towards there being only one. It's not clear why the rest of them can't just get along. Supposedly the last one will be given power over all mankind, but, they're immortal, so why?
 Which we never find out because there was never a sequel. What's that? La la la, I can't hear you!