The best thing you can do for elves, dwarves, fairies, and others is to either not make them long-lived or entirely remove them from the same tier as humanity. Some asshole blogger complaining about Mass Effect puts it better than I can.
>Imagine that right now, in Cambridge, you could find Sir Isaac Newton, Albert Einstein, Sir Edward Victor Appleton, and Niels Bohr hanging out with Stephen Hawking. And all of these guys are busy doing research, writing papers, and commenting on one another’s work.
>Imagine if we still had Da Vinci, Charls Darwin, Galileo Galilei, Marie Curie, Johannes Kepler, Nikola Tesla, Nicolaus Copernicus, Rosalind Franklin, Erwin Schrà¶dinger, Richard Feynman, and Carl Friedrich Gauss. Even better: Most of these people are still in their prime. None of them have entered the last century of their life.
>Galileo is pretty busy, but if you corner him at a party he’ll tell you all about hanging out with Al-Khwarizmi before his death in the 1700’s. And if you get a few drinks into him, he’ll wax nostalgic about the teachers of his youth, most of whom studied under Plato, Archimedes, and Pythagoras.
If we could live for centuries and stay physically and mentally fit for the vast majority of that time, we would have already made it to space or wiped ourselves out trying. Having a base of experts that can replenish itself exponentially faster than basic attrition could ever hope to deplete it is far, far too much of a benefit. Trying to handwave it away with elves only having babies once every hundred years or all of them being really lazy is going to make the players question you even more.