Timeshares are almost universally a terrible value. A lot of people get older and travel less than they used to and dump their timeshares just to avoid paying the dues, which is why resale values are so terrible.
The one exception has, up until this point, been the Disney Vacation Club. If you're absolutely sure you're going to want to go to Disney every year (and for a long time, not just for a few years while your kids are young) it could be a decent value because it insulates you from the price increases at Disney, which have far outpaced inflation. And if you do decide to sell and leave the program, resale values tend to be far stronger since Disney has a right of first refusal on sales that they do use. The problem is, though, that you're still making a big financial commitment to essentially one company. What if Disney, knowing that so many DVC members' trips are essentially guaranteed, decides to stop investing in and growing the parks with new attractions?