You don't have children, do you? I don't, but from what I've heard, children will really change your worldview in terms of the importance of your own life.
My problem with immortality is that you can't ever decide to die. There's no off switch, so no matter how tired you are there is no end. Also, immortality implies you have no need to eat or do anything, really. So it could be either liberating or hell depending on what sort of person you are.
I'm fine with living for a long time. Immortality means forever, and I don't want to think about what that might mean or how it would affect someone.
I find it hard to believe that the ruling sisters are totally invincible. Also the only consistent law of either universe seems to be that things change. Everyone dies. Dr. Who, Celestia...everyone. Having everlasting youth sounds awesome to me.