Everyone's habits and situations are different but it seems you can do well with DVC. Even if you're looking at spring break or Xmas, the numbers should work out to your advantage. You should know though that Easter and Xmas are roughly 135% the cost of summer and almost twice as many points as the lowest season. DVC could save you money and/or it could give you much better accomodations than you might get otherwise, depending on the choices you would make otherwise and how you use it.
The best comparision is a hotel room vs a studio and for staying at the moderates, it looks like you would come out ahead over time, but not by that much. You would however have a larger nicer room at a more upscale hotel for around the same price. Compared to the deluxe/premium options, you would come out ahead in this comparision. If your family is of such a configuration where you do or would later need 2 rooms, all of the above applies to a 2 BR as well. Even with a family of four, needing large or multiple rooms sometimes happen when the children are different genders or when others travel with you. The other benefits are the amenties such as laundry and a kitchen. Depending on choices and usage, these can be the difference. If you always eat out every meal, you savings with DVC will be less than otherwise.
If you're going for one week every year or 2 weeks every 2 years, you will need a lot of points. It will vary with specifics but in general you're looking at around 180 points per year for a studio every year for a week and 460 for a 2 BR. You would cut the number needed down to the 150 minimum and the 2 BR cost down to only about 350 by staying 6 days and avoiding one weekend night. Likewise, avoiding both Friday and Saturday nights would cut the cost to around 60% of the full week price. Obviously you'd need to make some decision and sit down with the
points charts to decide what's best and how many points.
You're original note sayid you went every 2-3 years, that would change my thoughts and recomendations somewhat. It doesn't mean it's not worth it, just that there are different considerations and the chances DVC will work for someone every 3 years is far less than every year to every 2 years. Many have joined with the idea of going every 2-3 years and now go more, as much as 2-3 times a year. Good luck.