Most of the people I know don't have children. And out of all of those, I've only had one say to me "You're lucky, you have children to take care of you when you get old." (lucky them!) And the person who said it is a lesbian.
Kids are great, but the minute you have one you take second seat. Your life, and for most part, your youth, are truly given to another.
Having "been there done that," I'd say, if you want one have one, otherwise leave it to others, there are enough people on the planet. And of course don't let those parents who soooo want to be grandparents influence you. They're not raising them.