It's crazy how hit or miss these can be. We've been staying at BWV for nearly 20 years ourselves and I can honestly only remember 1 time (I probably just jinxed myself for this summer) when we haven't gotten our request. Even that time, it was only one night and then they accommodated the request beginning the next night.
To answer the original question, our main request no matter what is always highest available floor. From there we generally request something relatively close to the elevators. To be honest though, the only request that we really truly care about at BWV is highest available floor. Main pool, quiet pool... both have some great spots especially now that you can see the fireworks at DHS from some rooms.