The Ship That Sails Itself to Valinor

The elves of Ithilien become really good at dealing with mortality through their closeness to mannish settlements and constant interaction with dwarves. They also get to better understand aging - so as Gimli gets older, because he's such a common presence in their lands, they all start being really careful in how they interact with him and what they offer to and expect from him. Sometimes Gimli is grievously offended by this, and sometimes grateful, but it all generally comes from a place of good intention.

Sad follow-up: Because of this new familiarity with mortality, the elvish settlement in Ithilien doesn't last much longer after Legolas sails. The colony starts breaking up almost right away, and by the end of a couple hundred years it's completely gone. Most of the elves who lived there also trickle away over sea, because they can't live in the world the way they used to, without noting the passage of time.