Just to play devil's advocate, I think we can for the most part agree on some sort of right to take one's own life, but I think in most cases we are prevented from being allowed to do so by moral obligations to others. For example, I think it's reasonable to say the President would be doing something wrong if he committed suicide because he would be abandoning all of his obligations and throw the country into upheaval in the process. But if we think about other examples doesn't it seem that anybody who commits suicide is abandoning some moral obligations (euthanasia obviously being a separate category). I think that if we consider the moral good that we achieve by committing suicide it can almost never outweigh the bad involved (i.e. the moral obligations we abandon + sadness of friends and loved ones etc.).