I've been debating about the whole child vs grandparents thing for a while. I don't think I could leave my kid(s) alone with my mother. I could see my dad asking them about inside information that is none of his business.
As for taking care of my parents when they're old, I wouldn't go too far. I would help them out, but not with money. It would also depend on my relationship with them. When I moved away from home, my dad got all wimpy and said, "Who's gonna take care of me when I'm old?" Then he told me that when he dies, he's not leaving me the house because of what I did (move out on my own)