according to my understanding of Tolkien was death, which is the ultimate change. The greatest ability of the human race is its mutability, or capacity for adaptation to change. For anything to be perfect, it has to be dead. I agree with (are you ready for this?) Genghis Khan: not perfection, but excellence, should be our goal. I think Tolkien understood the underlying principle quite well. Life IS change: only death is immutable (as far as we know, that is...)

As you say, Mabon, the Elves that showed the strongest developement and interest all had strong connections to human beings. Indeed, Elrond was half human, even though he chose to be Elven, and his children were given the same choice. Arwen Undomiel chose to be human, although her elven blood gave her an extended lifespan; I don't remember how Elrond's sons chose, or even if their choice was recorded. The Elves were called 'the Firstborn', but I think that was less a statement of preference than it was a simple statement of fact.