As the PP said, requesting a specific room number will likely decrease your chances of getting your request granted. Like most timeshares, DVC resorts tend to run at high occupancy year-round. The odds of someone checking out of the specific room you request on the day you arrive are slim.
Think about what you want in a room - high floor, pool view, close to elevator - whatever suits you. Then make that your request. If you have more than one request, make them in order of importance, your most important request first.