The best value in DVC, like other timeshares, is when you use your points within the DVC system. At WDW, that means: VWL, BWV, VGF, BCV, AKV, BLT, SSR, OKW. There's a DVC resort at the Grand Californian at DL, and DVC resorts in Hilton Head, Vero Beach and Hawaii.
Note that in the resorts I mentioned above that share facilities with a non-DVC resort, you may not use your points to book rooms in the non-DVC part of the resort. For example, you can't book a room in the CR tower or garden wing, only in Bay Lake Tower. To use points at WL, you'll be in the villas building, not the main building.
Currently, members who buy direct from Disney can also use points at Poly, YC, and the moderates, but you'll need to use a scary number of points for that. Since those are considered an exchange out of the system, the number of points required can and do go up every year, and the ability to use those resorts can go away at any time.