I'm child-free for another 5 weeks or so. I was happy without children my whole life, but I think I'll be happier once my daughter arrives. I'll be 40 in two months, and, honestly, you reach a point where life becomes the same crap over and over again and I think raising a family is probably an experience that cannot be replaced by any number of hobbies, friends, or amount of traveling. I think I was right to wait, as I'll be a much better parent now than I would have at 25 or 30.
Ironically, I think that most people who think they don't want children (usually out of a core of fear/immaturity), often times display the conscientiousness needed to actually be a good parent, and would often be better parents than the people who start pumping out multiple kids at 21 without a second thought.