We have 210. With two young kids, I thought that was more than enough, since it allows us to stay in a studio for over a week each year. Of course, once I started thinking about a 1 bedroom, I realized that I probably should have bought 250 so that I could stay in a 1BR for a week each year, or in a studio for two weeks. So, if/when I do upgrade, I will first add 40 more to reach that level.
If I were to really dream, I would like to get enough points to stay for a month. My wife and I are teachers, so we have time in the summer. And, of course, when we retire, my dream would be to spend at least a month of the winter in Disney. For a studio, that would be about 500 points, I think. I can't see myself adding that much in the near future, but hopefully someday.