I wish I could maintain that feeling I get when listening to Carl Sagan talk. Someone described it as "sober wonder", and it always dissipates from me in time.
I can relate. For me, contemplating my place in the vastness of time and space often induces a frame shift that improves the quality of my own behavior. Perhaps because Sagan spent so much time communicating those ideas, it became part of his personality. For related reasons, I don't think we can underestimate the effect that finding life elsewhere in the universe would have upon our cultural evolution.
Absolutely, I find myself a lot calmer, and I take a more holistic approach to everything. Eventually though I wind up reverting to my more temperamental self. At the very least, Sagan's effect on me has highlighted things I can go about changing. Finding life is another sobering thought that grabs me. How the world would react, all the different sects and cultures. Would the discovery unite or divide? I want to think it would be the former.
My guess is that it would tend to unite us. It seems to be part of our nature to find unity in contrast to something that is different. If we find life somewhere else, we can then only assume that there are countless other places where life exists and has evolved, and that we will find more life in time. Our place in the cosmos will be powerfully defined by that knowledge, as we become one example of many, and our fate is ours alone to be compared to that of others.