The common perception people have going into Stanford is that their lives are set and that everything's going to be fun and daisies. The truth is that the competition becomes tougher than ever, you will always be worried about getting into "the next step", and you will work harder than ever before. All in an environment where people are expected to be happy all the time and talking about your difficulties is frowned upon. Seriously, I didn't know this kind of atmosphere could exist until I came here.
Want to go to a school where you will be genuinely happy? I don't think Stanford is the place, though I am sure many people are very happy.
Want to go to a school where you will become even more competitive than before to the point of being cut-throat, never really show it, not really know what's wrong with the whole shebang since everyone looks so happy but something doesn't feel right and you'll start to feel too self-conscious about yourself and everyone around you? Stanford.
That being said, the academic quality is truly top caliber. If you are not entirely sure about coming here, I would not base my decision off of Admit Weekend which is not representative of how you will feel on a daily basis at all - try staying for a few days with a friend or something.
The competitive atmosphere you get at Stanford isn't the healthy kind where everyone's cheering each other on to succeed and everyone shares what they do - it's secretive and closed off, despite how open everything seems to be. The general atmosphere of the student body is "me, me" and there is little social activism or community work, and when there is it all seems overwhelmingly for themselves/ourselves. My biggest complaint would be the bubble. Like RCMan13 said (his observations are right on point) Palo Alto is a horrible college town. Students almost never leave campus, and on campus there isn't much to do either in terms of normal life. You will study all day and get really good at academics/test taking, but miss out on real-life events/work experience/everything else that your friends at less isolated universities are getting because the only people you are interacting with are students and professors, not a real-life community.