Somewhere between 15-20% of the rooms at BWV have a view of the Boardwalk/Crescent Lake. If you want one, request a Boardwalk view. (As far as I know, the only way to "guarantee" a BW view is to rent one of the 3-bedroom Grand Villas. They all have a BW view). Keep in mind that a BW view is the most frequently requested view and that supposedly, DVC members have priority over other guests. That said, it is not impossible to get one. Non-DVC members have reported that they were assigned a BW view room. Much will depend on availability of the BW view rooms on the day you check in.
If you just want a water view of some sort, there are many rooms that overlook the canal that goes from MGM to Swan/Dolphin Hotels. Some of these views also overlook Luna Park (feature pool with the clown slide) or the quiet pool/Community Hall area. IMHO, these are very pretty views, and you have a much better chance oif obtaining one of these views than the BW view.
Good luck and enjoy your stay! BWV is a wonderful resort!