There is a
DVC board on here that may garner you some more responses.
I am a DVC owner and I will say that it has not been difficult to get what we wanted. It doesn't mean that I get exactly what I want *all* of the time. I recall that I could not get into the Grand Californian DVC...so I booked the hotel instead when the hotel was still permittted to be booked. But IIRC, they were limited in their offerings and my booking window was small--which coupled together, meant that I wasn't getting the DVC.
Because of our size, I tend to go for 1 or 2BR accomodations and don't have too much of an issue. We do not fit in studios which sometimes (as I understand it), might present an issue at peak times if it isn't your home resort since they are the lowest points and may book more quickly.
I have had no trouble at 11 months out for my home resort of AKL. And my attempts to go to another property have been without issue including BCV for Memorial Day weekend one year, OKW and SSR, the latter two on short notice even. We are fairly new owners, so haven't gotten too far around the DVC family yet.
My next booking attempt will be for BLT, but we are a long ways away from my 7 month window. Advice provided was to book our home resort at 11 months to get what we NEED and then call member services at 7 months to request what we WANT. If it is not available, then we would wait list. But I have been told that I may be lucky since I need a larger accommodation.
Again, the DVC board will provide a wealth of information for you:
http://www.disboards.com/forumdisplay.php?f=7
Go and check out old threads and for any questions unanswered, they will be happy to help you!