I'd sign up for immortality real quick, but it always carries with it a tragic element. At best, you live to see all your friends, loved ones, pets, and favorite sports teams die, only leaving you to remember them. At worst, it carries with it all kinds of squicky implications. Do you age? What happens if you lose a body part? And what about your mind, both psychologically and physiologically? At some point, it seems like there are only so many memories you can cram in there.
I enjoyed the Nonmen in R. Scott Bakker's
Second Apocalypse series, among the gloomier extrapolations on a race of immortals. After thousands of years, the majority of them have succumbed to dementia, doomed never to die but existing in a state just above catatonia. A curious habit of theirs is to kill the people they love, since only the great pain of the action will leave an imprint strong enough to last the years.
Of course, The Culture takes a more optimistic approach. Also, there's a culture that trades in novelty right there for you. In
Hydrogen Sonata, you get to meet a 10,000 years old, and their doing just fine, by no means has extreme age dampened his joie d'vivre. The issue of memory is solved through technology, IIRC they're just storing it off-site. Same with
House of Suns by Alastair Reynolds, one of my all-time favorite novels. The Shatterlings have something called a trove, which let's them store all but their most recent memories (recent in the last millenia or so).
And on the issue of Reynolds, I also like his Ultranauts. Not quite immortal, but due to relativistic travel they end up skipping over long period of history, being perpetual outsiders. Because of this, and due to their technophiliac leanings and backstabby ship culture, they end up developing an extremely
outre society, rivethead/goth/metal/industrial culture taken to a hilarious extreme. You live long enough, it seems like it's hard not to be goth. But then that's just me.
I think the issue of memory has to come up, in some way of another. If magic is involved, then that's an easy handwave. But I'm still not sure how you would write a time abyss, no one in the world has that amount of life experience (I think). I guess plenty of authors have tried their best to approximate it and still succeed.
What do elves worry about?
The movement of the stars. The changing of the seasons. I view fae & elfypantskind as self-mythologized beings, not quite individual tangles of neuroses like use but rather personified archetypes. A certain godlike quality, like their identities are streamlined around a concept or element. Endless patience and self-reflection leads to a certain egolessness, perhaps they just seek to be the mirror upon the world outside of them. But, dunno, never met an elf. That's just how I see it.